https://www.facebook.com/help/174210519303259 - link or search in Facebook or Google.
To report someone who's pretending to be you or someone else, first determine if you're reporting a profile or a Page.
Meaning - Profiles, Page, Group.
Profiles
A profile is a place on Facebook where you can share information about yourself, such as your interests, photos, videos, current city and hometown. To see your profile, click or tap your name or profile picture at the top of Facebook.
Pages
You must have a profile to create a Page or help manage one. Pages are places on Facebook where artists, public figures, businesses, brands, organizations and nonprofits can connect with their fans or customers. When someone likes or follows a Page on Facebook, they can start seeing updates from that Page in their News Feed..
Groups
You must have a profile to create a group or help manage one. Groups are a place to communicate about shared interests with certain people. You can create a group for anything — your family reunion, your after-work sports team, your book club — and customize the group's privacy settings depending on who you want to be able to join and see the group. When you join a group on Facebook, you starting seeing content from that group in your News Feed..
How to report a profile or Page
If you have a Facebook account and want to report a profile or Page:
Go to the profile or Page of the impersonating account.
If you can't find it, try searching for the name used on the profile or Page or asking your friends if they can send you a link to it.
2 Click .... below the cover photo.
3. If you're reporting a Page, select Find Support or Report Page. If you're reporting a profile, select Find Support or Report Profile.
4 Follow the on-screen instructions for impersonation to file a report.