The general site menu (just below the site header) allows you to go to the pages for each domain category. Here, you will find interactive tables listing the available domain names. Each entry (i.e., each table row) comes with a hyperlink to the webpage of the respective domain name. You can find it in the table column “link to domain”:
To purchase a domain, just visit the page of the domain by left-clicking on this link. On the domain page, you will find the “Buy Now” buttons, which are also mentioned here:
Left-clicking on one of them initiates payment using one of the methods mentioned here.
So basically, you are just two clicks away from initiating your purchase.