I use a brass fitting that screws into the fluid filler at the helm. The brass fitting has a hose that attaches to the lid of the fluid bottle. Turn the bottle up and start turning the wheel back and forth all the way over until it doesn't burp out any more air bubbles.
If your steering still feels sloppy, you will need to bleed the air from the cylinder at the engine. Read the Sea Star manual but last time I did it, I turned the engine all the way to one side, barely opened the bleed cap on the opposite side and then turned the wheel until fluid sprayed out. Tighten the cap and finish turning the wheel all the way over. Then 'crack' the bleed cap on the other side and do the same thing. You will probably have to add more fluid at the help resevoir but the process is pretty easy.