its a big window but moveable and doesnt cover the entire screen and it wont let me fullscreen
because its not fullscreen, I cant see my friendlist
help

If you mean the launcher/lobby program, you can click the very 'top' of the application and drag it to the left, so you can see the bottom right corner. Hover over this corner and your mouse will change to the 'resize' icon.

Drag it to the size that fits your screen and that should fix it.

Hope that helps!

Have you tried clicking at the very top of the window (Where you can see the version number) and dragging it up a little?

There are two ways to get around this. You can either hide/shrink/move your taskbar, or you can resize the window. Resizing works, I guarantee it, so unless you ran into some really bizarre bug that doesn't let you resize...