Put text corresponding to what the clients will see after paying if you have choose an URL to redirect to (after using PayPal or others).
Link to put on PayPal to redirect to, is this way:

http://www.your-site.com/pay/done.php?after=12345678

Codes to put can be changed but not name of files!

65381151 (code After 1)
67381762 (code After 2)
65385753 (code After 3)
55381753 (code After 4)
65381557 (code After 5)
65351668 (code After 6)
86538575 (code After 7)
76538175 (code After 8)
65381151 (code After 9)
21381151 (code After 10)
22381762 (code After 11)
23385753 (code After 12)
25381753 (code After 13)
26381557 (code After 14)
27351668 (code After 15)