Help with setting up Subscription correctly on Membership

In home stretch of setting up Membership on site, but having difficulty figuring how correct sequencing to move interested customer through subscription process. Right now, I have subscription form that seems to lead directly to my payment gateway correctly, but missing the step how do I get the customer registered into the site. Am using the "default" pages in the Membership Options sections for this. Thanks for help - I have studied manual but am sure I am missing a step along the way (mostly because I am neophyte at setting up this correct sequence, I am sure!). Thanks again! Kerry