If you have sources, add the sources and make the changes if the profile has the 'Edit' button visible. If you don't have sources, then you can add comments below the profile or add a section called Research Notes with your information. If you have information from ancestry, those can be added, preferably with a good citation and a link to the viewable image.
Do you have information from a Genealogy book for a surname or location? Many of those are online so a link can be added to those sources. We have wikitree space pages where there are links to many of those.
If you have information to add to a profile, especially with sources, and the profile is not open for editing, you can leave a comment on the profile, send a private message to the PM, or request Trusted List, which can be done from the Privacy tab of a profile.
Just remember that frequently there are multiple people with the same name, and sometimes same wife name, in the same area and within related families. If you have used ancestry for your relationships and research, their hints and many of their 'sources' come from other peoples family trees, not necessarily from actual sources.
Adding sources to profiles is what make wikitree different from the other sites.