Generate the url that allows my user to give me their paypal and become affiliate

Hello,

I am trying to build a similar page on my website to https://premium.wpmudev.org/affiliates/. How do I generate the URL that I give to my users to allow them to give me their paypal info? (Similar to step 2 on your affiliate sign up page:https://premium.wpmudev.org/affiliates/)

Best,
Ming