enabling uid and userPassword attributes

I am planning on utilizing OpenLdap as a repository for users and authentication credentials. I have installed the software and edited the slapd.conf specific to my domain. In slapd.conf, I noticed that it includes core.schema, so I took a look inside this file to see what fields (attributes) are specified. The 'uid' and 'userPassword' attributes are commented out and since it is recommended not to edit this file, I was wondering how I go about enabling these attributes? I have already tried creating another schema file and including that in my slapd.conf, but when I attempted to run, it stated that those attributes already exist.

Thanks in advance, Jeremiah