Open up RDGTE and open the language file (of prefered language) (ALWAYS BACKUP ORIGINAL FILES!!!!)
Scroll down until you see this:
Change the name you want to change (for example: RUBENS becomes TIAGO, BARRICHELLO becomes MONTEIRO)
WARNING: NAMES LIKE NICO (Rosberg, Hulkenberg) changes both the drivers names!!!!
Then for the teams scroll up until you see this:
Change the team name
Violá your done!
There is ALOT more you can change, but this is really the basic