How can seller and buyer complete a transaction protected by "Buyer&Seller's protection"?

[A_Poplas]

I'm trying to buy an item posted on the website, which can't use direct PayPal's integration of payment (so buyer and seller complete a "direct" transaction using PayPal). How can seller and buyer setup a transaction between each other in order for both of them to be protected by Buyer&Seller protection? 

Thanks.

[sharpiemarker · Accepted solution]

@A_Poplas 

Seller can send an invoice, or the buyer can send a goods and services payment from your PayPal account.