You can emulate a right mouse click using the keyboard, by enabling mouse keys.
I know there is a lot of information on that webpage, so if you don't want to read it all, you can enable mouse keys by pressing the left ALT, left SHIFT and NUM LOCK keys together. A mouse icon should then appear in the system tray, if it has a red cross on it, hit the NUM LOCK key several times to remove it.
To use the mouse keys, the numeric keypad on your keyboard has these functions.
The system tray icon shows which mouse button is currently active.