That is a good question & fairly easy to answer.
If you have tied flies for any length of time you are used to putting a hook in the vise then tying your favorite pattern. Tying tube flies is somewhat the same basic process except you tie the fly on a hard plastic or metal tube. Depending on your vise there is an extra piece needed to tie these flies. It is called a mandrel. Basically it's a simple strong wire in a clevis that clamps in the vise, or like me you make your own. My Peak vise would not except the HMH mandrel, so I made my own tapered pins from a coat hanger along with my stand grinder. Once you have the mandrel head for the fly shop, or on-line (www.flyfisusa.com
is where I bought my first supplies, they had better prices than my local fly shop) & purchase a package of the tubing. In the package will also be some flexible tubing. Cut a piece of the hard plastic tubing about an inch long. Get a butuane lighter & place the flame close to one end & you'll see the tubing roll back on itself forming a collar. Use your bodkin to make sure the tubing is open that you just heated. Take a piece of flexible tubing about 3/8" to 1/2" long & slide it over the rolled end of the hard tubing around 1/2 halfway. It will stay in place. Slide the tubes onto the mandrel & tie your fly right on the tube. Whip finish & repeat the tube roll back on the other end with the lighter. Your done. Feed some mono or tippet thru the tube & tie on a Diachi X510, or other short shank straight eye hook. Once the hook is tied on slide the eye up into the other end of the flexible tubing & you ready to fish your tube fly. Check out Tube Flies
for some short tying videos that will explain it more. When I first started tying tube flies I researched the net & found some sites that had tying videos which helped to get things going for me. Also check out some write-ups on FlyFisherman.com: The Virtual Flyshop
. One of the main advantages that works for me is that you can have a 4" fly targeting Steelhead, or Salmon with a small #4 or #6 Diachi X510 & have better hookups & much better landing percentages than with a normal long shank hook. ( you'll see this in the write-up I mentioned earlier ) Hope this helps. I know it helped me when I asked questions.
Try them & you'll be hooked :-)
Tie One On--------------<*))))))><
Fisher of Men