Hi there Paul,
The easy answer is that you upgrade to better clubs by purchasing them with credits from the Pro-Shop. As you get better and move up through the levels more and more clubs become available for you.....either putters, irons, wedges and drivers etc.
For instance....you are at level 26 so if you go to the pro-shop you can buy anything from level 1 to level 26 at present......if you look in the Pro-shop you will see that this driver (below) is there for you....but you have to `BUY IT` and then equip it !
Hope that has helped you a little....and I not saying go and buy that driver as there are many to choose from at your level.
Good luck in your search...
Listee x