To get to the advanced pattern search, click the Patterns tab and then click Use the pattern browser & advanced search. From there, you'll see a list of potential filters along the left side. I've created a video tutorial for how to use these filters, so you can watch the video for an overview of how this search works. Below are the filters I recommend you use if you want to try to find a pattern for a specific yarn in your stash.
Choose one (or more) of these filters if you want to narrow down the search to the type of craft (knit, crochet, machine knit, loom knit).
Yardage (or Meterage)
Use this filter to find patterns that use the amount of yarn that you have. You can either check off the box(es) for a pre-listed range or you can add your own specific yardage under customize.
Choose the weight of yarn that you have. Notice that for fingering weight, there is "light fingering" and "fingering." If you want to be very specific, pick the one that matches up with your yarn. Sometimes I like to check both so I can see all options and then decide whether or not that pattern will work with my yarn.
Any selection you make here will filter patterns based upon the yarn(s) the designer has listed as recommended yarns. This is especially helpful if you have a fiber such as alpaca or bamboo with characteristics (growth!) very different from wool.
Colors used (typical)
If you have just one color of yarn, you should check the box next to 1. However, if you have more than one color in your stash that you'd like to use together, you can check one (or more) of the other boxes to find patterns that use 2 or 3 (or more) colors.
You can search for patterns based upon a specific gauge. This is helpful if you have made a swatch of your yarn and you want a pattern that will work to the same gauge. This is not a necessary filter, but I wanted to mention it in case you find it helpful.
This search feature has many other options (I go over many of those in the video) that you can use to narrow your pattern options. But if you want to match a specific yarn to a pattern, using the above filters will help you find patterns that will work with your yarn.
Happy pattern searching!