About my home coax cabling

I just bought a internet plan with xfinity (the self-install equipment will likely arrive tomorrow) and I know that the router needs a coax to connect to the internet. The thing is I also have DirectTV satelite from AT&T that also uses coax so I know that it's probably not a good idea to use a coax thats also connected to the satelite, but I'm not sure if I have a coax that can connect to the router that isn't also connected to the satelite. I'm not sure where the first coax that enters my house ends up because theres one coax at the front that enters through the walls of my garage, but the the satelite dishes are in the backyard. Is it best to get a technician to install possibly a new coax line or xfinity box so that theres no interference with the new internet?