To set up the standard kit that you will get from the tackle shop put the parts on to your line in this order, bead, float (coloured end first ), ball weight, bead and then the swivel. Tie up a hook length, about 30 to 40 cm long and attach this to the lower eye of the swivel by putting the double overhand loop through the eye and then passing the hook back through the loop and pulling up tight.
The stop to prevent the bait and weight sinking right to the bottom is formed by the small elastic band you will find in the kit; put the band around the line above the float and put one end of the band through the other and pull up tight. If you have large eyes on your rod you can leave it like that.... if the band catches on its way through the eyes you will need to trim off the free end of the band.
You can now slide the band stop up the line to set the fishing depth.
For a cheaper and more versatile set up have a look at my rig here