If I am making my own font in Illustrator and I want make the middle of the letter delete so you can see through it. For example, I'm making the letter A. How would I take the middle out? Thanks.

I don't know about making fonts but you can make the letter into an outline, then select it and make it a stroke.

Select the object.
Bring up the Color Window. (f6)
In the Color Window there are the two overlapping swatches. Clicking on them will put a line through them, which will deactivate them for that object. So click on the solid swatch to deactivate it and it will then be empty. Click on the swatch that is an outline (Stroke) and give it a colour.

Now you have an object that has just a stroke value.

You'd be better off creating the font in a program such as Fontographer. You have vector editing tools, and it exports to .ttf with all the options and stuff.