Whether you are a mentor looking to join the community, or are a designer looking for help, the first step is to create an account and profile.
For now, scroll the list and find a designer that has a background or experience that resonates with you. Get to know their work, visit their personal site or twitter to see what they are passionate about!
If you find someone that stands out in the group, don't hesitate to reach out to them! The only mentors listed on this site are people who submitted their info, which means they are more than happy for you to reach out to them.