I am very new to blender and am trying to make a model for a game called gmod. I am wondering how do I make an edge curved (I don't think I'm saying that right) as seen below.

Oh and if I add a subdivision surface modifier it does this:

I am very new to blender and am trying to make a model for a game called gmod. I am wondering how do I make an edge curved (I don't think I'm saying that right) as seen below.

Oh and if I add a subdivision surface modifier it does this:

You could need both subsurf and/or bevel, depending on what you need.
Here's an example, starting from a box extruded and shaped to a similar starting object:
the edge trick is shown on the right wireframe: adding edges near subsurfed rounded corners, you get somewhat sharp edges if you need them, but leaving subsurf for the rest of the mesh...
Hth