Glass is tansparent, but I didn''t want it to be?

Of course it was upside down and too small, then facing the wrong way, but now that I got that all fixed, I noticed the glass is transparent, but I made it a solid texture because I wasn't sure how to even make it transparent yet! Go figure. I didn't build a cockpit, or put in a pilot HP, so now you can see right thru the thing.

How can I make the glass *not* be transparent? Else I'll have to build a cockpit and redo all my hardpoints, because I don't think I could build one in milkshape, I have a hard time with it.