You can update these information using the options in the top right box of this site.
During the seminar (usually after the first deadline) you should have receive an invitation into the Program Committee (PC) of the seminar.
This the a prerequisite for the creating reviews, hence make sure you accept the invitation a.s.a.p.
After the deadline for the review versions, you will be assigned as reviewer for two other submissions. You will be notified by mail when the assignment is done. Enter the EasyChair page of the seminar in your PC member role.
Click on Assigned to me in the Review menu and download the paper you are assigned to review (submission column with adobe pdf symbol). When you have read the paper and you are ready to write the review click on the + button to create your review.
Complete the review form and submit it.