GEDmatch is a great site for DNA enthusiasts. It can take raw dna files exported from pretty much all the big dna testers: Ancestry, 23&me, FTDNA, etc.
it can get a little tricky to export your dna data file from Ancestry. I recommend you go to YouTube and search for “how to export dna from acncestry to GEDmatch” and you’ll find a bunch of videos that will step you through the process.
GEDmatch has many valuable comparisons for free. I pay an extra $10 for 30 days (they offer a one time fee or you can auto renew) for advanced features like triangulation. Once you upload your dna, you will get a kit number, or “GEDmatch ID” like “A123456”. That’s what wikitree is asking you for.
There is another site called a RootsFinder, free thru summer, that has excellent visual graphs of triangulation. It can also suck in a gedcom, wikitrees, or familysearch trees.