there should be a section in your /etc/httpd/conf/httpd.conf file related to user directories. it will look similar to the following code.
to enable user directories, uncomment code as necessary, or start from scratch in a new secton. specify the name for the folder you want to use (i.e. public_html), set options, and restart (or graceful restart) httpd.
the users (or you) can then create a public_html directory and be sure that the httpd user has access to read the contents. so the public_html directory itself probably needs permissions of 755. the users need to make sure their content is readable by the httpd user too, which usually means making the files world-readable. alternatively you could set the sticky bit for them to be sure permissions will work no matter what they do.
AllowOverride FileInfo AuthConfig Limit
Options MultiViews SymLinksIfOwnerMatch
<Limit GET POST OPTIONS PROPFIND>
Allow from all
<LimitExcept GET POST OPTIONS PROPFIND>
Deny from all