i hav made an aircraft, a model of an f-5 tiger, but bits are all seperate. Can someone tell me how to merge all the pieces into one mesh, as when i try to export the piece, adding all the different bits as lods, it makes the .sm file, but when i reopen it to check it, all i get is one of the pieces of the aircraft. Please help, i need it so much.

Help me every-one, you're my only hope.