In order to create Multiple Fleets, you should have already created your first one. This means that you are probably accustomed to the way the Fleet Management page works.
Once again, you need to click on the CREATE FLEET button in order to start adding vessels to your Fleet. You may either search for each vessel, or opt to Import IMO/MMSI numbers. Either way, you will need to select your new Fleet name and colour, if the latter is available for you. Afterwards, you will just need to click on CREATE FLEET and your new Fleet will be created!
Moreover, you can create a new Fleet from the Explore tool as well. When you have finished a search, and you have found more that one vessel that you want to add to a new Fleet, you have the option to select multiple vessels and create a new Fleet with a click of a button!
Click on the adjacent button on the left side of each result to select it. The selected will appear green and a new button will appear on the button that reads Add to new Fleet. Type a name for your fleet, select a color and click Create.