WP eMember should already be set up on your website with all the basic levels that you would need when we initially designed your website.
However as you go along you might find that you need to add additional membership levels and of course you need to protect your content.
WP eMember has created extensive documentation on their website.
Check out their website WP eMember Documentation Index for loads of information on how to do different tasks.
Most of the information that would be relevant will be under the “Design and Usage” and “Payment Membership Option”.