You really have to wait for them to come to you with a problem, or at the very least, give them an optional lead in (e.g. "I was having trouble with #{subject x} last night as well, but I think I've got it now. You want me to see if I can't figure out what's got you stuck?"). That way you aren't forcing your way in, or coming off as "I'm smarter than you, just come over here and I'll explain it idiot", which I've seen happen plenty of times (and have done it myself a few times, I'm sure).
On the other hand, once people do start coming to you, you'll find you understand the topic better at the end yourself, and they'll greatly appreciate the help. If done right, they probably won't hesitate to come back for help again, which ends up in another win-win situation for you. Just don't swing to the other side and end up doing their work for them!
On the other hand, once people do start coming to you, you'll find you understand the topic better at the end yourself, and they'll greatly appreciate the help. If done right, they probably won't hesitate to come back for help again, which ends up in another win-win situation for you. Just don't swing to the other side and end up doing their work for them!