I don't have pictures but the process is pretty straightforward:
1. Collect a bunch of cottonwood cotton (the cleaner the better)
2. Pick the obvious bits of sticks, leaves, seeds etc out of it
3. Ideally, card it with cotton
cards, or some fairly fine, soft carding equipment or brush (I frequently don't bother with this step for just a small amount, but if you want a really uniform smooth yarn this makes it much easier)
4. Spin it with a small lightweight drop spindle, or a wheel that's good for high twist short staple yarns. What wheels work best are probably going to be really user dependent, since every handspinner has his/her own preferences. The main thing is to put
enough twist in the yarn that it doesn't fall apart, but not so much that the yarn ends up stiff and ropey. Also, how much twist you want to put in is somewhat dependent on what you plan to do with the yarn. If you want to weave with it but are only using it for weft you won't need as strong a yarn as you would for warp.
5. Ply it as desired (again dependent on what you want to use it for --a plied yarn will be stronger than singles, especially for beginning spinners or when first learning how to spin a new fiber).
6. Wash it. I always wash things in lukewarm
water, probably because I'm lazy and don't want to have to think about it, but I actually recommend experimenting in this case, as there isn't a lot of information available about it and we might as well start researching it.
7. Dry it under tension --this is what people usually do for cotton yarns, and often for other fibers also. It helps to "set the twist".
8. Try to be patient --it always takes a while to learn how a new fiber behaves. If you're not feeling patient then I'd recommend blending it with some kind of wool --even a little bit can make all the difference, as wool is very forgiving and practically spins itself, so you don't have to pay such close attention.
If I have time later in the spring when the cottonwoods are shedding their cotton, I'll see if I can send some pictures. Some willows around here also produce a lot of cotton some years, which is also spinnable but tends to be even shorter staple, requiring more attention and patience, but still doable.