Just follow instructions i wrote here :
http://www.racedepartment.com/forum/threads/start-career-with-any-team-mod.56278/ Even trained monkey can do that.
1. Backup database.bin
2. Edit database.bin following my instructions (choose team you want to play with and SWAP its ID !!! with MARRUSIA team) with latest Ryder database editor found here
http://petar.outer-heaven.net/downloads/. Save. Overwrite old database.bin with your edited one (dont forget to backup original!)
3. START NEW PROFILE and do young driver test Day 1 WITH RED BULL OR FERRARI!
4. Exit young driver test after day 1 and Start your career.
If someone cant follow this then i really dont know how make it easier....