Enter your mtDNA results at www.mitosearch.org and say for now that your haplogroup is M
When you save you will likely get an error message. Go to MitoSearch and search for people with the M haplogroup and find your self. Make a note of your MitoSearch ID. Change your haplogroup from M to your actual haplogroup.
Then enter your MitoSearch ID, haplogroup, etc. on your DNA Tests page at WikiTree.
Change your privacy level at WikiTree from "Private" to "Private with Public Family Tree" then within 24 hours, your mtDNA information will automatically be associated with your direct maternal line.