Please do send us an email at firstname.lastname@example.org so we can create a partner account for you. We will give you ways to create accounts for the users you sell to.
There are two ways for this.
The first way is the simpler one. You create an HTML page and place your PayPal buttons and you're done. The only downside is if you need to charge your users additional tax when selling (EU VAT for example or other). If you need to charge a tax go to 2.2 Buttons with Tax in this article.
To create a page with simple Buy Now buttons follow this guide: Get PayPal Buttons without Tax for Your Sales Page
To create a page where you apply tax to the buttons follow this guide: Get PayPal Buttons & Added Tax for Your Sales Page