With my first attempt I was manually entering the information from my DNA matches tree into a new tree on my account. I titled the new tree DNA Mirror Tree. I made it private and non-searchable like you are supposed to do so other people don't see it and get confused.
I think the biggest problem I had was since I was trying to manually enter the info there just wasn't enough information on it to get any shared ancestor hints.
I learned just recently a much easier way to make a mirror tree. I have made my very first video every showing what I learned. you can see it on YouTube at: youtu.be/l0cQLwpII6A It is 28:21 minutes long.
I had my daughter watch it because she has only helped me a little bit and really has no experience working with trees. She said it was "Very informative!" So hopefully newbies and experienced ancestry users will find it helpful.
So using this new method I have created a new mirror tree and will attach my dna to the person who is my DNA match. Then I will give it a week for Ancestry to search its database for DNA matches that have Shared Ancestor Hints with the mirror tree.
I will report back on if I was successful or not. Course part of the problem may be that I am a predicted 4th cousin with this DNA cousin and I watched a video that said mirror trees work best with predicted 2nd and 3rd cousins.