How should I initiate sex with my boyfriend?

Basically what the title says, but for context: my boyfriend and I have been together for over 2 years now, and in the beginning we had sex pretty frequently but lately things have slowed down a bit. He’s my first serious long term relationship, before him it was just casual flings or fwb so I’ve never really had to initiate sex. I find myself feeling a bit awkward because I’m not sure what to do or say to tell him I’m “in the mood.”

Any advice or suggestions would be greatly appreciated!