Each affiliate's link is your site URL with ?ref=AFFILIATE-ID (shown on the Affiliate Users list, the affiliate's edit page and their own dashboard). When a visitor arrives through it, Sprwt stores the affiliate ID in their browsing session (only if no ref was already stored that session). If the visitor then registers, the new account is permanently attributed to that affiliate with today's date as the attribution start (method Link). Existing accounts that click the link are not re-attributed; use Assign User for those. The affiliate's Link Generator lets them build the same ?ref= link for other pages of your site.