Go to the insert text button on the left. A window like this should pop up.
after you type in the text you want (in the case 3d) press ok
When you press Ok text should be in the file now. the current project it 10 frames the more frames you add the longer it will be. 100 frames is about 7-8 seconds.
so go ahead and make the file 100 frames long. It is along the top.