I (25F) am a beginner at sexting. Need help on how to sext.

Hi All,

I (25F) am currently in a live-in with my bf (30M). Unfortunately, I've to shift out of town for work and while we were discussing various stuff, he said he was looking forward to sext once I go there. Now the thing is that I've never sexted in my life. I didn't want to disappoint him so I said Yes. What should I consider while sexting? how do I start? is there any guide which can help me with this?