You will be very well off if you read and 'digest' the Salt docs on States first, before moving on to modules, pillars, grains, custom returners, etc.

What you probably need to do with logrotate is take the configuration that you normaly setup on your servers, then add it to your salt system. So top.sls calls 'logrotate' running the 'logrotate/init.sls' and that has a definition that says "I want logrotate installed, I want it running as a service, and by the way take the file 'logrotate/config.conf' and shove it in /etc/logrotate.d/ as <correct filename>, p.s. If i change that file, restart logrotate"

With States & the requisite declarations to enable salt to know what order things need to be in, you shouldnt have much trouble adding a simple service like logrotate along with a specific config file to use for that service.