How do I let a guy know I'm interested in hooking up with him?

I'm a relationship kind of girl typically, however, the dating thing hasn't been going so well for a while now and it's been a really embarrassingly long time since the last time I got laid. I'm not the type of girl to go out, pick up some random guy I don't know and have sex with him. I've only ever had a single one night stand and it happened kind of by accident (alcohol was involved). I'm also kind of shy, which doesn't help. So I really have no idea how to let a guy know I just want a casual hook up.

There is a guy I know, he's sort of a friendly acquaintance I guess. He's been confiding in me about his problems for whatever reason. He is recently divorced. His wife cheated on him because he was "not paying enough attention to her" since he was working 60 hours a week to pay their bills and support their kids after she lost her job and made no effort to find another one. They tried to "fix" things a few times but she kept going back to the guy she cheated with. I know he's in no position to pursue a relationship and frankly, I don't want a relationship with him, but he's easy on the eyes and I feel comfortable enough with him that I think it wouldn't be too weird to hook up with him.

He has blatantly said to me twice that he hasn't had sex in forever, which I let slide at the time but after the fact, I was thinking maybe that was a hint?

I'm not sure how to get my interest across to him. We only ever see each other in a place where there are typically several other people in close range so it's not like I can initiate it there (no, he's not a coworker). But there is room enough to at least get out of earshot of others. We're not friends on any social media and I don't have his number. I invited him to a concert once and gave him my number so he could let me know if he wanted to go. I was thinking maybe if I could get him to go, I could make a move then. He acted like he was really into going but never called/texted and when I saw him again, he claims it was in his wallet and he accidentally left his wallet in his pocket and put it through the washing machine. Could be true, could be BS, I don't know. I think he may have thought I was asking him on a date and, like I said, I know he's not ready for that so maybe he just felt uncomfortable. How do I let him know I'm interested in hooking up?

I'm doubting the washing machine story but I cant think of any guy who wouldn't want to hear that a woman is interested in hooking up with him. Especially after a divorce. His ego is probably a bit bruised anyway. I think the key is a bit of tact but be upfront. Guys can sometimes be idiots and some of us need to be told frankly. A concert could have been construded as a date and a date might be the start of a relationship. Being newly divorced he may not want that but you two seem to be pretty open on the sex tip.
Ask him out for a drink, no pressure and while there let him know you need the same thing he does. human affection.

I should have added that the concert was a group thing so it wouldn't have been just us and he knows a couple of the other people he went. I guess he still could have thought it was a date. I don't really buy the washing machine story either though. I've heard my share of BS lol

I thought of asking him out for a drink but I was thinking he might take that as a date too..

I don't think a guy would tell a girl he hasn't had sex in forever if he wasn't interested. Ask him for a drink and then have more than you should ;)