Sure thing piper:

The fuel dot is basically a pretty termination point for a third, separate fueling line to your fuel tank. Many fuel tanks (certainly the Great Planes and DuBro tanks) have attachment points for these separate fueling lines.

Due to the fact that there's very little distance between the firewall and the needle valve connector in my Venture 60 I added a separate fueling line to the tank. You COULD just leave the fuel line dangling in the engine compartment and seal it off with a screw if you've not got a fully cowled engine, but it's neater to use a fuel dot.

The fuel dot consists of two pieces: the hollow receptacle that the plug fits in to, and the fuel line plug. First you drill a hole through your cowl/airplane side of the same diameter as the fuel dot. Next you fit the fuel dot receptacle so that the attachment nut goes on the inside of the cowl/airplane. Tighten the nut so that the fuel dot receptacle is firmly attached (it's an idea to use thread-lock compound or a drop of thin CA on the thread so that you don't lose the attachment nut during flight.) Next thread the fueling line through the fuel dot receptacle from the inside to the outside of the aircraft. Finally insert the fuel dot plug into the end of the fueling line, then click the fuel dot plug/fuel line into the fuel dot receptacle. This seals the end of the fueling line and secures it to the side of the aircraft while still leaving it easily accessible from the outside.

Personally I wouldn't worry about installing a separate fueling line on your trainer if there's enough space to easily remove/attach the fuel line from the needle valve. It's really a very simple and effective method of refueling your aircraft, and has the added benefit of one less fuel line attached to the fuel tank (and therefore less chance of developing a leak in the fuel system) and one less hole through the firewall/aircraft side. As I said, I'm really only doing this because of the space constraints in my Venture. Well, that and it looks cool

Hope this helps,
Neil.