This might help:
1) Bring up tabs for Find-A-Grave (for a specific cemetery), Wikitree (Category->specify same cemetery), and a second Wikitree tab so you can search if the Wikitree profile already exists). If the Wikitree Cemetery does not exist, after you have created the first profile, you will need to request the cemetery Category be created.
2) View the memorials at the cemetery you have chosen. For the sake of sanity, start with the first memorial provides fairly complete dates. Search on Wikitree for that person. If not found, go on to create the profile on Wikitree using the following as your first source (that you will replace with the Family Search Citation when it is available).
URL:
https://www.findagrave.com/memorial/205754475/walker-thunder
you will then create the profile and add some biographical information if any is available on FG.
Since Wikitree does not recognize FG as a great source for several reasons, always go to Roots Search which is a link under RESEARCH on the wikitree profile page.
3) Understand that it is easier to find sources for people born before 1950 as that is the last census that has been released.
4) Add the sources you choose and add the cemetery Category or request one be created.
Please note, the information from the church or cemetery sextant is always more desired than the Find-A-Grave information.
Also, Wikitree is a wonderful community. We want to encourage new genealogists to join and to learn and others who have more knowledge than ourselves to add to the profiles.
Embrace collaboration.