1st part is simple. Go to
http://www.mdapplicants.com and add your profile.
2nd part is a little more complex: I think you will see many recent applicants take steps to "hide" their stats. It is possibly an urban legend that the ADCOMS look to the mdapplicants site and see if the applicants match their potential interviewees. I think the worry is that the schools may try to avoid applicants who may not be serious about their school. I don't know if it is reasonable, but who knows....
Same reasoning holds true for SDN-you may not want to complain too much or reveal too many weaknesses on the chance that the ADCOMS read it and associate you with a profile.