[Chimera-users] merging 2 pdb files

Hi, My name is Adrian. I am a graduate student at Bar Ilan University in Israel. I have 2 pdb files, each containing rRNA sequences and I would like to combine the 2 to make 1 pdb file displaying all of the rRNA subunits. I download the Chimera program. Is it possible to do this on your program and if so, can you please tell me how? Thank you so much, Adrian