This post relates to these discussion forums rather than the game itself. The advice (except for the quotations section) can also be used for writing your Blog Posts or messages on The Walls of other users.
In response to a question received on the wall, here are brief instructions on how to insert quoted passages, links, pictures and smilies into your WGT forums posts, and how to color your fonts.
As of July 2009, there are still quite a few bugs in the forum software (for examples, see here, here and here). WGT forum's Compose editor by itself is quite nice, because it's WYSIWYG (= What You See Is What You Get, similar to MS Word). At the same time, it offers advanced users the option to click the 
button and edit the raw source code of their posts, if they wish to do so.
Nevertheless, if you want to quote another user's words, insert a smiley or color your font, this is currently (July 2009) only possible by using rather cumbersome workarounds, described below. If you don't feel discouraged by that, read on.
Inserting Quotations
If you want to quote what another poster said before you, due to the bug described here you can only do so manually before publishing your post. So, to quote someone, you need to copy & paste (CTRL+C, then CTRL+V) the other person's words into the text of your reply, and then surround that passage by the following:
[quote user="username"]quoted text[/quote]
The result looks like this:
username:quoted text
For double quotations, use the following format:
[quote user="Bonnie"][quote user="Clyde"]How are you, Bonnie?
[/quote]Thanks, Clyde, I'm fine.[/quote]
The result looks like this:
Bonnie: Clyde: How are you, Bonnie?
Thanks, Clyde, I'm fine.
Inserting Links
First, highlight the words you wrote that you want to make clickable. After they are highlighted, press this button on the toolbar: 
. The Insert/Edit Link mini-window will pop up for you:
Enter the address to which you want to send the readers of your post in the Link URL field, then press the Insert button. Done.
Inserting Smilies or Pictures in Forum Posts
- You need to locate on your computer or on the Internet the picture you want to insert into your post. You may then simply try highlighting the picture (for example, a smiley) with your mouse, and directly copy it to your WGT forum edit window via CTRL+C and CTRL+V. If, however, what you'd like to insert is the picture of your scorecard, you first need to make a screenshot of your scorecard. (Press the PrtSc key on your keyboard; open a program such as Paint; insert, via CTRL+V, the screenshot you've just made; cut away the unnecessary parts of the screenshot; and save the screenshot on your computer via CTRL+S.)
- Then, as you write your WGT forum post, press the green Insert Media button
on the toolbar. The Insert Media mini-window will pop up for you:
Locate the picture you want to insert into your post on your computer after pressing the Browse... button.* Or, if it's a picture on the Internet that you want to insert into your post, paste (via CTRL+V) that picture's (that smiley's) Internet address in the Media URL field. Finally, press the Insert button. Done.
A categorized collection of smilies is available, for example, here: smile.vdp.sk. Just highlight any smiley with your mouse, and directly copy it to your WGT forum edit window via CTRL+C and CTRL+V. If that doesn't work, you may right-click with your mouse the smiley you want to insert into your forum post, and get the smiley's Internet address. (In Firefox, it's the Copy Image Location menu item. In Opera, it's the Copy Image Address menu item. In Internet Explorer, you first need to click on Properties, then get the address from the Address (URL) field.) Once you have the smiley's Internet address, you can insert it, via CTRL+V, in the Media URL field in the mini-window pictured above.
* It currently (July 2009) appears the Browse... button inside WGT's Insert Media window is broken. After you press it, nothing happens. So, you can upload your picture (such as your scorecard) to the Internet, and link it from there. You can publish any picture online by going to (for example) imageshack.us, pressing the 
button, locating the picture on your computer, and pressing the 
button. The ImageShack software will generate the picture's Internet address for you in the Hotlink for forums (1) field, surrounded by the [IMG] and [/IMG] tags. Another similar online service is at tinypic.com.
Coloring Your Fonts
You first need to click the button on the toolbar of your Compose window. Then find the words that you want to color in a certain way, and surround them with the following HTML tags:
<font color="purple">text to appear in purple color</font>
The result looks like this:
text to appear in purple color
Instead of the word purple, you can insert any other standard color name recognized in HTML. See here for a list of 120 nice, standard HTML colors. (Once you click the Update button in the HTML Source Editor window, the forum software will automatically convert the tags and color names entered by you, into CSS tags and numeric color values, but you can just ignore that; it's the way it should be.)
Decreasing / Enlarging Your Font
You first need to click the button on the toolbar of your Compose window. Then find the words that you want to appear in a smaller font, and surround them with (for example) the following HTML tags:
<small>text to appear in a small font</small>
The result looks like this:
text to appear in a small font
If you want something to appear in a bigger font, you may use these tags:
<big>text to appear in a bigger font</big>
The result looks like this:
text to appear in a bigger font
If you want something to appear in a very big font, you may use multiple tags like these:
<big><big><big>text to appear in a very big font</big></big></big>
The result looks like this:
text to appear in a very big font
Another related tutorial: How to Post Your Scorecard, in Seven Steps.
If anything is unclear in these instructions, please let me know on my Wall or here in the forum, and I will update the above wording accordingly.
(Updated on 5 August 2009 to include instructions on double quotations. Updated again on 29 August 2009 to include instructions on how to decrease/enlarge fonts in forum posts. Updated again on 20 September 2009 to include the direct-copy method for inserting pictures, especially smilies, into forum posts.)