We've removed our old largely non-functional wishlist feature: it was confusing, and it didn't operate like you expected, and often didn't even work right so you couldn't see what items were in your wishlist.
We are replacing the old wishlist with a new one that should be much more intuitive to use. Adding to the wishlist is as simple as clicking anywhere on the red text when looking at a puzzle's product page:
You can get to your wishlist from the pop-up in the corner after adding an item or by clicking on the link at the top of the website:
If you want to access your wishlist on more than one device, you'll have to link it to an email address. To do that use the gear icon when looking at your wishlist and put in your email.
If you find any issues with the new functions let us know in the comments - it'll be much better to figure out what works and what doesn't soon when it's still relatively easy to make changes.
EDIT: Thanks Tonia for pointing out the lack of a link on mobile - we've made some updates and there should now be a heart icon right in the middle of the top of the screen you can click on to get to your wishlist if you're using your phone.