How to buy MBS bonds?

Excuse me, could you please elaborate on the process of purchasing MBS bonds? I'm quite new to this and I'm trying to understand the steps involved. Specifically, what do I need to do to get started? Do I need to open a specific type of account? And where can I find reputable dealers or exchanges to purchase these bonds from? Also, what factors should I consider when choosing which MBS bonds to invest in? Any guidance you can provide would be greatly appreciated.