I want to give a back massage to my boyfriend but I’m not sure how to do it

UPDATE: i just got back home from his place. I gave him a full back massage with lotion i own and i gently rubbed his shoulders. You know how cats make biscuits? I did something similar with the palms of my hands. He said that’s the best massage he’s ever gotten and that I’m his favorite XD. I even got him to fall asleep which he’s been having a hard time doing recently. Thank you to the ones who responded 💜

This is my first time posting on this subreddit so bear with me 🙏🏻

So my boyfriend is going through something in his personal life, and he’s been having an extremely hard time sleeping because of it. Tomorrow I’m going over to his house towards the evening, and I want to surprise him by giving him a 30-ish minute back massage. In his lower back on his spine kinda close to his tailbone he’s been having some major pain because he fell on his butt trying to skateboard. I can’t remember exactly what he said about it, all i know is that he’s in pain constantly but not to the point he can’t do things. He also has a lot of acne on his back. Mostly scars, so I’m wondering if it’s okay to use lotion on him, if anyone has any techniques they’d like to recommend so my hands don’t get tired too quickly, and what will help relieve him of his physical stress.

I did try to google my questions, and nothing of use came up besides this subreddit which the post was from 3 years ago didn’t really answer specifically what I need. Thanks!