Yes, you can assist a friend in signing up for an account, However it is better to give your friend your unique referral url that is provided to you in your welcome email.
If you friends clicks the link and signs up you will be eligible to earn 10% of any of their earnings. Most models use a url shortener such as http://bit.ly to shorten their referral urls to make it shorter and to hide their profile name. This way your friend or whomever you refer does not know your own profile name. You just collect the 10% referral earnings.
