You will be given a lounge invitation for the F lounge at check-in. If your flight departs from the gates 1-32, turn right immediately after security to enter the F section of The Wing. If your flight departs from gates 33-80, you might wanna use The Pier. Take the APM and walk towards gate 63. The entrance of The Pier is very subtle.
If time permits, you can visit both lounges. If that's what you want make sure they stamp "Lounge Re-entry" on your BP.