GTA objects collision

[Lex]

We're doing a map mod with my friends, but none of us know about making a not solid to solid object, if one of yoyr experience about doing map with map editor.

Ramps and other stadium props aren't solid or what we call a collision thing, is any of you know about fixing this problem, I would appreciate any help.

[AllBeast]

make collision from 3ds example with coleditor 2
name must be same as dff model
and if it is vice city, collision must not have too much polygons