You will have to go to a well known dig site, carefully extract the fossils and the rocks entombed around it. The dating is usually done on the rock crystals in which the fossil is entombed, or igneous strata directly above or below the fossil.So...
... were should I start searching for fossils? Have someone seen my T-rex fossil, it should be here somewere?! After we plunder his grave we can use that equipment to date its age, can't we!?
Here are the most famous fossil sites.
NOVA Online/Curse of T. rex/Where to Dig/Sites
You may need a permit. Check your local natural history museum.