Hi! You go to Shareasale, log in and click on this link:
http://www.shareasale.com/a-customproductlink.cfm

Then in the Drop Down box, pick Viator. This is a *very* important step, or your links won't track!

In the box labeled "Destination URL:" Put the link to the page you want to link to.

Click Create Custom Link.

The tracking code for that link will be generated. You need to a<a href=" to the front of the link and ">Your text for the link</a>

If you need a lot of links, go to:
http://www.shareasale.com/a-download...rchantID=18208

And download the datafeed file that has all the links to all the tours on Viator. There are both image links and landing page urls in that file, along with other information that is detailed in this thread.