Go to www.schoology.com
Click Sign Up
Click Parent
Type in the access code that was provided by your child's homeroom teacher.
Type in the required information then click Register.
After you get registered you can add additional children to your account:
Click your name in the upper-right corner.
Click Add Child
Type in the access code that was provided by your child's homeroom teacher.
This quick 5 minute video provides a great tutorial on using your Schoology parent account to view your child's work.