If you tested your MtDNA at Family Tree DNA their help pages are quite well done. Another place to look is WikiPedia.
On WikiTree, if you have entered your Mitosearch ID into your profile and provided your privacy controls are set to yellow, green, or white, your DNA data is propagated to your daughters and to all direct line maternal female ancestors and their daughters.
To search for someone with your haplogroup you can search wikitree by going to search, scrolling to the bottom and using the global search for any characters. You may have to try a few variations on it to get it to work. I just tried with mine - H1a1 - and found a lot of people.