Short version is that it's pretty unlikely (but not impossible) that the stamps have much value. You can go to a library and borrow a Scott's catalogue so you can identify which stamps you have. Scott's shows a "catalog value" which is always highly inflated. The important thing is to look for any stamps which have a value of $20+ or so. Those are the ones to look for because they have a shot of being sold.
In reality, a stamp with a catalog value of $10 or less is about impossible to sell to anyone.
If you see multiple variations of a stamp in Scott's (not unusual, because some stamps have different size perforations, colors, etc.) then you'll need someone with more knowledge to help you figure it out.
