how to add more groups to mounts and files?

I was going to mount a windows share via mount.cifs and using dir_mode. > mount -t cifs //server/share /mnt/ -o > user=username,dom=domain,dir_mode=0755,uid=510,**gid=610** This means only members of group id 610 will have access to it. But how can I add more groups? In general I am asking myself how to set more groups to files in linux? For example: > drwxrwxr-x 3 Adrian HomeGroup1 Foldername In this case only HomeGroup1 has rwx permissions. How to add more groups?