Click the little triangle next to Properties to open its drop-down menu. In some ways this is similar to the Title drop-down menu in Premiere's workspace menu bar. Its primary purpose is to define the size and spacing of your text.
I'd suggest you enter some text in the text window and then change some of the following Properties values to see their effect:
Typeface? Use the drop-down menu to choose from 90 fonts and from each font's available style (bold, italic, and so on).
Font Size? The default is a very large 100. Change it to something more manageable.
Aspect? How fat or thin each letter is.
Leading? How much space there is between text lines.
Kerning? Spacing between letters on a line.
Tracking? Spacing between letters within the entire bounding box.
Slant? Tilts letters either to the right or left, depending on whether you use a positive or negative number. This is great if you want to give text that "speedy" look.
All Caps and Underline? Just like in a word processor.