index=%yourIndexHere% websiteName=* | timechart span=1d count by websiteName limit=0
This should work..brings back all events with "websiteName" present, then counts them per day with no limit on how any sites it will count for.
Be sure to add any further criteria to identify your events before the pipe to timechart. ( ie "LOGIN FAIL")
you could also use the bin command with stats command, but timechart does both anyhow and this gets you the visualization.
*I threw in the limit=0 in case you have a large amount of websiteNames. The default limit is 10 everything outside 10 would go to "OTHER".
To obtain the number of daily events that matches your search criteria for the month of June 2015 per websitename, try this:
your search criteria websitename=* earliest=”6/1/2015:00:00:00” latest=”6/30/2015:23:59:59” | timechart span=1d count by websitename limit=0
By using limit=0 you will return all values (default is limit=10)