The two lowest level Ops you can join are Eternity Vault and Karaggas Palace. Those are story Mode Ops and you can queue for that once you hit 50 but it is suggested you get at least Columi gear to start those. You can queue for them in Group Finder. They are the two at the top. Once you have completed one you are locked out for a week.
Why would you get Columi gear to run an operation that drops Columi? You get a free set of Tionese gear when you hit 50, put it on, wear your pvp relics and recruit earpiece/implants, and queue for SM OP's via GF. You are more than enough geared.