If you are just trying to get air out of the line (ie the system isn't dry), put one of the pencil tip attachments onto the mity vac (use a short line from vac to bottle, long line from bottle to pencil tip. Make sure the resevoir is filled to the top of the notches inside. Put the tip into the resevoir, and pump once to get some fluid into the line. Don't take the tip out of the resevoir. move the tip around the bottom untill you feel it go into the hole on the bottom. Push down a bit, and pump the vac to about 20-25 psi. Keep the line as straight up as possible. Wait a bit and you will start to see small bubbles. Wait a little longer and you might see some big bubbles. When you are satisfied, pull the release trigger with the tip still in the fluid, and let it all run back in. Pull the tip out and let any fluid still in the line run into the resevoir.
Fill the resevoir again if needed, put the black thing and cap on, pump the clutch a few times, them do it all again.
If the system is dry, its easiest to bleed out of the car. You can hook the slave and master up out of the car (if you can) and put a piece of tubing over the bleeder valve on the slave, crack it with an 11m wrench, put the end of the tube in a bottle of fluid, put the tip of the vac in the top of the resevoir, and pump it up a bit. You can do the same on the car, but its a pita to get at the bleeder valve.