This help page explains our thank-you page Redirection features:
http://www.e-junkie.com/ej/help.redirection.htm
Normally, you would just leave your Common Thank-you Page URL setting blank, to use the standard thank-you pages we automatically generate for you; this is especially recommended if you are selling downloads, so your buyers will be able to obtain their downloads immediately following checkout.
If you would prefer to redirect buyers to a page on your site after checkout, you would enter the URL of that page as your Common Thank-you Page URL. In this case, you should probably also remove the [%thankyou_link%] template code in your Common Thank-you Email template (or just delete that template to disable that message), as that link would just redirect back to your site's Common Thank-you Page URL.
