This article requires you know how to set up embedded content. If you do not know this or need a refresher, take a look at this article.
Both cross and up-sell work by using the category attribute that is associated with your content items. Lets talk about two example to make sure this is clear:
Up-Sell: When trying to up-sell, you want to promote a more expensive product in the same category as the item the visitor is currently interested in. Let's say the product he or she is looking at is a MacBook. The thing you would want to recommend here is a more expensive MacBook. This requires you to have both items tagged with the same category. In this instance this would probably be "MacBooks". The algorithm will be able to look at all items within the category and use the information for up-sell.
Cross-Sell: Let's take the same visitor from the previous example and promote cross-sell. Instead of recommending items based on a category, the algorithm can check what items are often looked at together, in the shopping cart together bought together (ascending order of weight for the recommendations). This does require the conversion script to be implemented.
Note: You can check if your categories are set up correctly in your items by following the steps in this article. This is necessary for Up-Sell.
Once you have made sure your categories and/or conversion scripts are set up correctly, we can dive into the touchpoint itself.
First, set up a touchpoint for the Website - Embedded.
Now filter your content to limit it to products, you can also filter it to only show in stock products. If you have products in multiple languages, make sure to also filter on this.
Third set up your appearance tab with the CSS selector and editor. Unclear on this? Check out this article.
It is very important to set the audience settings for this touchpoint up properly. You only want this touchpoint to show when the visitor is on the product page. You can do this by selecting Is on productpage / equal / true. You need to set this up because the CSS selector might also be on other pages and you do not always want to show it. Not using the correct audience targeting can also have a big impact on the speed of your website touchpoints.