I can explain it a bit ...if you already do have a paypal account you can "add a card" or link it with your bank account...paypal will then transfer the funds over ...it does seem to be an automatic response by paypal itself...
I use my paypal that way ...my donation comes right out my bank account through paypal and put here for the forum..
I would suggest to link your account or credit card/debit card to your Paypal..it is very straight forward and easy to do...
I hope that helps some....