PAKate, it sounds as if you have the basic text editor in place. Try this:
Click on "Settings" in the dark brown box on the very top on of the screen (next to your name)
Scroll down until you see "My Account" under ""My Settings" on the left. Click on "General Settings"
Scroll down until you see Miscellaneous Options on the right. Click on the radio button next to "Enhanced Interface- Full WYSIWYG".
Click on the Save button to save your changes.