Seriously, when I bought my first DIY loom kit, I cannot loom. I don't know how to make the chains, too. After I borrow my friend's loom bracelet, I tried to imitate its loom chains, but well, the results are not so bad but not so good, too. At least it makes me happy.
Okay, now I want to show you how to make loom chains!

Step 1: Technique 1

The first thing to do is gathering the materials (loom bands, hooks, etc.)
(Pic. 1-3) Place 3 bands; a band in form of number 8, and two band in form of 0. Using the hook, make it clamp the other two loom bands.

(Pic 4-5) now place another band under the clamp (hanging), form it like a C form, and slip another band under it (see pic. 5)

Now follow the instructions until the loom chains are long enough for your purpose.

Step 2: Result of Technique 1

This is an example of a technique 1's loom band's bangle.

Step 3: Technique 2

(Pic 1-2) Do the same thing like technique 1's first things to do.

(Pic 3-5) Slip the hook under the hanging loom band, place two loom bands near the hook on the top, and pull the hook so the the loom bands are like in the 5th pic.

(Pic 6-8) Slip the hook between those two loom bands, place another loom band near the hook, pull it again (see pic 8).

Do the steps again and again until the chains are long enough for your purpose.