S2Member provides a powerful internal capability to create PayPal payment buttons in both the framework and the Pro versions. The Pro version offers additional features which will not be explored on this page. There are other payment gateway options available but again, not covered on this page.
Go to the Dashboard (backend) of your website and select the S2Member section (see the first red arrow in the screen capture to the left). From the drop-down, select PayPal buttons (see the second red arrow). This will open the selection panel for all the various buttons you can create.
Note that this is the Pro version showing on the left. The basic Framework version will have less options but the PayPal Buttons link will be the same.
From the PayPal buttons selection panel (first image below) select the access level you wish to create your button for. That will open the button creation panel (second image below). In this example I opened the Level 2 panel. The structure is identical for all four (paid) levels. I've marked the important sections with red arrows.
Unless you want to offer a trial period, skip line 1. In line 2, enter the amount you will charge and the period for which the charge applies (subscription term or one time payment). In line 4, enter a description of the package you are selling. In line 5, enter any Cusetom Capabilities (if any) for this package.
Click the blue Generate Button Code link and then copy the code from the WordPress Shortcode box. Use that code where you want the button to appear on your page.