"you wanna see these melons?"
Tell him exactly what you want to do to him. For example:
You looked so good the other day...I just wanted to pull you away and have my way with you. I'm dripping wet right now, I wish you were here. I'd do whatever you want.
first of all, only sext if its gonna lead to actual sex, otherwise the tease will just be frustrating.
second of all, pics should be sent with discretion and only if you truly trust him, a lot of guys keep the pics and when there is a fight or break up and use those pics for revenge. some get the pics to show them to their friends even when they're not angry.
and third, just tell him what you want him to do to you and what you want to do to him.
one example would be: I want you to grab my ass with both hands and kiss my neck.
or: I want to kiss your chest lower and lower till I go a little too low.
you know what I mean?
play with yourself as you sext him...the truth will come out then.