Need help looping songs

[Tradermon]

Hello all, i'm trying to add some of my own music to project m and brawl, and i'm kinda stuck on looping. I know brawlbox has a looper and all I need to do is put in the start and end points, but i'm having trouble doing that. The loop I wanna make is long and I don't know how to do it for audacity or goldbox. For audacity, I figured out how to loop but I don't know how to make it so I don't have to listen to the entire loop to test it. Do I have to lock the loop points or something? Any help is needed!!!