There are quite a few resources to use to get you going with Miva Merchant. Here are a few that we recommend:
http://manual.westhost.com/part8.html#miva-config
http://www.miva.com/docs/
http://www.mivahelp.com/
All are great places for information, some may be more useful to you than others. Hopefully this will help get you where you want to be.