Is it an easy process to purchase a brokerage CD?

Happy new year...

I'm looking at my bank it's gotta be new money. Is it a simple process to purchase a brokerage cd at vanguard? I only know about going to a bank and opening up a regular ole cd. Nervous to do something like that on my own. It shows at vanguard for like 1-3 months I can get 4.1. I'll take that as the money market i have at bank is like high 2's at the moment. If you suggest it's a good idea, it's best to go with a NON callable cd, correct?

Thanks