I'm not sure how to help with the fishery as I'd need to know how you've set everything up. Here's how to get some different threads though:
You'll need to know how to enable labours on dwarves so they do the jobs you want them to. I assume you know how, but if not you highlight them with the view units command [v], go to preferences [p], labours [l], and then navigate that menu for turning labours on and off. Or, you can download a program called Dwarf Therapist which makes this a million times easier.
Anyway...
1) Making rope reed thread/cloth:
- Designate an area for plants to be gathered with [d], [p] (and hope you gather some rope reed)
- Build a farmer's workshop [ b], [w], [w]
- Order the rope reed to be processed at the workshop [q], [a], [p] (+[r] for repeat)
- Build a loom [ b], [w], [ o] if you need to turn the thread into cloth.
Note: you will need dwarves with the "plant gathering" (herbalist), "plant processing" (threshing), and weaving labours enabled.
2) Making yarn cloth:
- Build a farmer's workshop [ b], [w], [w]
- Order an animal to be sheared [q], [a], [ s] (+[r] for repeat).
- Order wool to be spun into yarn at the same workshop [q], [a], [shift+s], (+[r] for repeat)
- Build a loom [ b], [w], [ o] if you need to turn the thread into cloth.
Note: you will need dwarves with the shearing, spinning, and weaving labours enabled. You will also need animals that can be sheared.
Note2: If you already butchered those animals, you normally get left with the wool as a product of the butchering. If that wool was dumped in a refuse pile outside, you may need to let your dwarves know they can pick up refuse from outside using the orders menu. Use [ o] orders, [r] refuse, [ o] outside.
3) Making cave spider silk cloth:
- Dig down until you breach a cavern.
- Build a loom [ b], [w], [ o]
- By default, looms will automatically generate collect web jobs for weavers.
- By default, the same looms will probably turn the cave spider silk into thread.
Note: you will need a dwarf with the weaving labour enabled.
Note 2: the caverns can produce tough wild animals and monsters - you might want to seal it back up afterwards, or build drawbridges and doors for extra security.
4) Alternatively, trading for cloth:
- You will need to build a trade depot [ b], [shift + d]
- You will need a dwarf appointed to the position of broker using the nobles screen [n]
- You will need trade goods to sell (or any junk you don't need anymore).
- You will need to keep your fingers crossed that traders come before the dwarf goes nuts.
Note: a trade depot, like a few other buildings, needs a dwarf with the architecture labour enabled before it will be built.
Edit: Frickin' formatting! Grr...