Here is the process I used (it is fairly complex, but the "Help" button can be your friend!):
1) After logging into www.WikiTree.com (which is totally FREE!!), I went to my "Navigation Home Page:"
2) In order to find a relationship, I need to find the person of interest. In this case, I selected Alan Shepard. I put his name in the search box at the top of the screen above (in the red box). I clicked on the "Search" icon and the program found all of the persons named Alan Shepard in WikiTree:
Alan Shepard the astronaut is the second one on the list (you could use Wikipedia.org for famous persons if you are unsure of birth and death dates).
3) I clicked on his name on the above screen, and saw his WikiTree profile:
4) Obtaining the relationship is a two step process - first you run your mouse over the "My WikiTree" link at the top of the page (in the top red box on the screen above), which opens the dropdown list of operations you can perform. Down near the bottom of the dropdown list is "Relationship to Me" (in the bottom red box on the screen above). I clicked on the "Relationship to Me" link (two screens shown):
It took awhile (about 60 seconds?) to create the page above, but it worked. The most recent common ancestor is listed - in this case, Stephen Tracy - along with the trail from Alan Shepard back to the common ancestor, and then it shows the trail from me back to the common ancestor, plus a statement of the relationship - in this case, Stephen Tracy is our 9th great-grandfather, so Alan Shepard and I are 10th cousins.
That is an excellent informational page about the relationship.
5) But there's more! On the page above, I put a red box around the "Explore more" box. This tells me that Alan Shepard and I share 318 ancestors in common in WikiTree, back to the 25th generation. By clicking the green down arrow in the red box (shown below), I can see the list of the 318 persons who are our common ancestors, and I can click on any one of them to see the relationship trails:
The list is ordered by the number of generations from the ancestor to the target person and to me.
6) I really like this feature in WikiTree. Not every relationship may be correct because there may be errors in the research of the users who contributed the information, so I can see if there is another relationship in which I have more confidence.