What is the difference between static meshes and regular 3D models. I am very new to game development, and I am using UDK (Unreal Development Kit).
According to UDN's page on static meshes:
"A Static Mesh is a piece of geometry that consists of a set of polygons which can be cached in video memory and rendered by the graphics card."
There really isn't much of a difference, other than that static meshes as UDK understands them are stored inside a package, (often if not always) associated with a material and a collision mesh, and usually have LODs which are themselves separate "regular 3d models" (though these can be automatically generated by Simplygon from inside the UDK static mesh editor).
I suspect you're asking "How can I import my 3d model into UDK, and use it as a static mesh?" in which case, there are a number of ways. The basic rundown is:
Of course, there are finer details to consider regarding UV setup for Lightmass, smoothing groups, etc., but those will all depend on your 3d authoring tool.
If you're just getting started, I would recommend taking a look at 3dbuzz' "Creating a Simple Level" video series. It requires (free) registration, but they cover all the highlights of what goes into using your assets in the UDK.
Basically, they're cheaper to draw if you say that they don't animate.