I "highly" recommend NameSilo, which is the least-expensive domain registrar.
Transferring a domain is simple. The following link should answer your questions:
https://www.namesilo.com/Support/Dom...sked-Questions
If you continue to have questions, write to support at <support@namesilo.com>.
You won't regret moving your domain to NameSilo, and you'll save a few bucks when doing so.
Good luck!