Go to the picture of the Hammer on the right tab (It's in the same line as the modifier and create bar) and click on it. You'll find a list of tools. Click 'More' then scroll to "Textporter." Open it, then you'll see a Height/Width section. Set those to what you want, then select the model you want to textport. It'll open up a picture of it, and you can save this to whatever file type you want.