Directions to North Ave Beach Using Cta?

Okay so me and my friends are going to go to the beach this week, We were planning using the Cta. The green line (harlem/lake) is the closest one to our house. How would we get there using the cta. We'd have to get off at clark? i think. im not sure what to do from there. Please help, im not good with using cta and all those kind of things. I appreciate it!