Northstar is one of the more crowded (if not the most crowded) resorts in Lake Tahoe; and being this is a holiday weekend, it's going to be a shit show. If you're taking lessons though, you should be fairly isolated so don't worry too much about running into others. Good luck and have fun!
I went to Northstar earlier this year and it was pretty crowded. It wasnt even a holiday weekend. I'm a beginner too (just started riding this year, only been 6 times) and found that it was pretty fun once you were out on the slopes. Plan on spending a lot of time in the lift lines though.