Hi Brian,
If you click on a yellow ball (mooring icon), provided you are close enough to the quayside where you are to moor, then the bollards on the quay will light up yellow also, then click on the bollard you wish to use and the mooring rope will appear, and the mooring point on the ship will turn red. To unmoor click on the red point and the mooring rope is freed. Green balls are towing points which operate in a similar fashion but will activate tow ropes instead of mooring ropes. The green stars are waypoints which you have to travel to with your ship. red buoys are to be passed to port in Europe but to starboard in USA. Green ones are to be passed to Starboard in Europe but to port in USA. The blue ball indicates the ships anchor/s and when clicked will lower the anchor. do not do this at speed as you will probably wreck your ship when the anchor bites!!!!
If you play "Tutorial mission 01" most of the questions you ask will be made clear and you can experiment with the various mooring/ unmooring, anchoring, deploying boats etc. You will find the mission in your "Single missions " list. An explanation of the buoyage system can also be found here as well as a simplified note on the International regulations (COLREGS) :- http://forum.shipsim.com/index.php/topic,20837.msg281515.html#msg281515
Angus.