Unfortunately, you probably will not be able to wear your glasses under your mask. There are a couple of options however. First, try to get fitted for some contact lenses. They are quite inexpensive now and I use them for surfing and simply throw them away after a few uses. Also, if you plan on soing quite a bit of snorkeling, you can have prescription lenses mounted right into your mask so that you can see perfectly.
Have a great time!