Seo digger is an SEO tool designed to help you track your site and your competition in google. How to use it might not be apparent right away. Here is a suggestion to get you started.
First you need find the keywords you rank for. This research is pretty easy if you are using google analytics. Click "traffic sources" in your account to see where your search traffic is coming from.
To find all the keywords you rank for click full list under the keywords tab. You may discover some keywords with this tool that you did not expect to rank for.
Add these keywords to seo digger to make sure they are in our database.
Now look up yourself and your competitors to see where you rank for these keywords
After that the seo is up to you. Optimize for the keywords you want