once you have the object files placed in my_objects, go into the game and to tools, then to object maker. In the second panel simply type in the .mesh bar, objectnamehere.mesh and hit add new. To save it to use in maps, go back to the first tab and name the object in the top bar, and name the group you want it to go into in the one below that. If this kinda confuses you i can take a screenshot to show ya xD