how to add objects in omsi editor?

how can i add objects in omsi editor? for example a building?

What ya mean?
Do you want to create some buildngs or just use the existing ones?

i will use the existing buildings, but how can i load a new building, a church for example? did you know what i mean?

Yes. Simply start the Editor, choose "Objects" and then press the small button "Load All".

ok thanks