I started playing FO1 on GameTap and it's fun. But during a fight with a rad-scorpion it said that my gun dropped. How do I get it back?

Pick it up (no, I'm not being smart).

When you drop a weapon, or any item, you'll find it at your feet. Just pick it up like any other item on the ground.

Sometimes it gets lost in a pile of dead bodies, I don't know how to get stuff back when that happens.

Yea, that's exacty what happened to me. I had already killed 2 scorpions and I guess it fell "between" them. I just reloaded my last save. Thanks for the heads up.

Ah yes, the old "I dropped my gun and it fell under that dead guy" situation.

It's always a good practice to not stand in the corpses of fallen enemies, for exactly that reason.