I think your question is how to tie jigs on poured jig heads?
There are two pieces of equipment that will make it a lot easier. The first is a fly tying vise. If you don't plan on really getting into fly tying for trout, etc, then you can get by with a cheap vise. They come in two different mounting configurations. One type clamps to the edge of a table/desk. The other comes with a heavy base and is called a pedistal vise. You can find examples of both in a variety of price ranges on ebay in their fly tying amd materials section.
The other tool that you will need is a thread bobbin. While it is possible to tie with the spool of thread in your hand, a bobbin that holds the spool will let you put the thread on in a tighter and neater manner. Again, they come in a variety of sizes and price ranges. For tying jigs you don't need the most expensive. But, those with a ceramic insert into the bobbin tube tend to do a little better.
Here are the simple steps:
1. Secure the jig head in the vice where it is tight and doesn't move.
2.Start your thread with overlapping wraps over the tag end to secure it to the hook. A knot is not needed. There are thousands of videos on U-tube showing this first step as it is the same for all fly tying. For jigs, you can use heavy rod wrapping thread down to about the 6/0 size. It comes in a variety of colors and can accent your jig.
3. Hold your prepared material (squirrel tail, etc) around the hook at the head and tightly wrap the thread. It may take a couple of tries before you get it very tight but don't break the thread. Secure the body material down with a bunch of wraps. Thread is cheap and will do a bunch of flies, so don't slack on that step.
4. Finish off the fly by 5-6 half hitches over your thread wraps. That makes sure the thread doesn't loosen and cause your material to slip.
5. Use some clear nail polish over the thread wraps and half hitches. That really locks everything down.
It is a bunch of fun to make you own jigs, and gives you the ability to have some that often aren't commercially on the market. I used to catch a bunch of crappie on jigs I tied with fox squirrel tails, and little white/chartruese feathers.
Have fun!