Posting an open Fleet Invite
From EVE University Wiki
See also Fleetwindow and fleetfinder
Putting a link to an auto-invite fleet is a two-step process, after the Fleet Finder was introduced with Dominion
Start out by forming a fleet with yourself - click the fleet icon in the left-side menu and create a fleet.
Then go to the "Fleet Finder" tab and the "My Advert" sub tab. Be sure to set the fleet to "Alliance only" and give it a nice description:
After the fleet is prepped and submitted, it is now visible to others in the alliance.
Switch to the "Find Fleets" sub tab and you should see available fleets, including your own. Now simply drag your character picture to a chat window:
