What is your experience of foreplay? Or masturbation? Are you familiar with touching your own body? What feels pleasurable?
I think you just have to tell him "I'd really like to sleep with you but I've never done that before. Can we go very slowly please?" Ask him to spend a lot of time kissing you, stroking your body, making you feel turned on, before he goes anywhere near your genitalia. Touching usually starts over clothes then progresses to underneath clothes or getting undressed.
If you are relaxed and enjoying yourself, your vagina will naturally lubricate. You'll get wet. If you're not wet, he needs to keep going until you are.
When you're ready he can touch your vulva. If he strokes your clitoris and labia, it should feel nice. You might like him to use his mouth and tongue there.
It would be sensible for him to try inserting a finger before full intercourse. If you've used tampons or inserted your own finger then you probably do not have a hymen anymore. If you do have a hymen, any penetration might break it. It could hurt momentarily and bleed a little bit.
Only when you're ready, should you progress to him inserting his penis in your vagina. Missionary position allows you to look at each other so he can check you're ok. It feels a bit weird the first time but shouldn't be painful or uncomfortable. It's not like a smear where you're tense, you should be relaxed and feeling turned on.
If you are unhappy at any point, tell him. Communicate the whole time. Tell him if it's nice. Or if it's not.
Please make sure you use a condom to avoid pregnancy and STIs.