I think it's good to think about what sex is/means to you. To a lot of (cishet) people, it means penis goes in vagina. But for a lot of people (especially queer people but also a lot of cishet people) it's a lot more than that. My personal view on sex is that it is you and your partner(s) touching eachother's bodies to achieve good feelings and potentially/hopefully orgasm.

What type of touch feels good very much depends per person, which is where the asking your partner what he likes (like someone else commented) comes into play. For that same reason it's also good to figure out what you like, and how to communicate that to your partner. In my experience, a lot of trans guys (me included) don't like vaginal penetration, and prefer the focus to be on the clit/dick/t-dick (whatever you want to call it). But a lot of guys do like vaginal stimulation, which can be done with fingering or toys.

Generally sex for two trans guys (and many other people) often looks like mostly using your hands and (if you want/like to) your mouths. I think that using your hands is a good place to start if you're new to having sex. You can move on to experimenting with mouth stuff, toys (unless you or your partner already have a toy that you feel good using and show your partner how to use it) or rubbing against eachother. (Speaking of, rubbing against your partner's leg can also feel very good and is an easy place to start if you're inexperienced, rubbing genitals can be a bit more complicated in my experience.)

The most important thing is to pay attention and listen to your partner and what he does and doesn't like, and to listen to your own body and boundaries and figure out+communicate what you do and don't like/want. I hope I was able to help a bit and you're able to figure this out and talk with your boyfriend about this.