When a person first comes to WikiTree, they create a Guest account. With that account they can look around on WikiTree, do research, upload a gedcom file for comparing their ancestry to what is already here, enter the DNA results of any tests they have taken. They cannot add any family tree members. They cannot add their parents, grandparents, children, etc.
Once they have created their research Tags, volunteered and been confirmed as a Family Member by a WikiTree Greeter they may then do all of the above plus they may add their direct family line – parents, grandparents, aunts, uncles, etc. They may not edit Open profiles that are not in their family line.
When a Family Member signs the Honor Code, they have all the responsibilities and rights of a full member. They may add unrelated individuals to the family tree, they may edit Open privacy profiles, and any other privilege that a full member has.
If you want to help a Guest, your best help would be to advise them to complete their research tags and volunteer so they can be confirmed and get the information that all new members receive.