To create packages as a reseller you will first need to login to the WHM panel as the reseller user.
Once logged in go to packages
Click the Add Package link to get the the package creation form:
In the example image I have filled out some basic account resource limits but you are free to set these as you see fit.
Please keep in mind that you will not be able to assign a dedicated IP address.. If would like to have that option there is cost for that.
When you are finished setting the package resource limits click Add to add the package.
