From MEPIS Documentation Wiki
The chown command is used to change the owner of a file. Typically, this is done as root to shift ownership from root to a user. The user is usually identified by a login name, though there are other possibilities.
To change a file, open a terminal and become root, then enter
chown UserName NameOfFile
If you need to change a folder and all its contents, then add the switch -R (for recursive):
chown -R UserName FolderName