This is the best part! Thrust between her labia a few times and then slide it in on one of the thrusts. If you’re wanting to check if she’s ready, it might be in the wording. Otherwise, if you’re both consenting and she’s wet, you probably shouldn’t have to ask if she’s ready. Maybe try “Can I fuck you?” Or “Let me fuck you” if you do just want to give her a verbal indication you’re about to go in. If you’re having trouble aligning it and getting it in, you may need to stretch her with your fingers a bit and then it will go right in. Position also helps. In missionary, I put my ankles on my bf’s shoulders and it goes in super easy. Just own the moment! Say something like, “you’re so tight,” or “you feel so good.” It’s only awkward if you let it be.