Lead guitar and
Nightrain is a pretty easy song - the intro doodle is just the same as the vocal chorus so you can't get lost there. The verse riff is just repeated over and over so that is fairly simple too!
The solo isn't too long or challenging, so ya should get on fine with that too
What do you mean play together?? All you gotta do is keep in time with the drums! When your practising at home, just keep playing along to the actual song and get the timings right. If everyone does that, then when you come to jam you all know what to do at what time