I've worked in a few different fabric stores before, and I was amazed at the many customers who came in and didn't know how to make any craft at all. What is worse, they often didn't know basic sewing techniques. To me this is a great shame. Clothes and other fabric items can be easily saved or improved by stitchery. If you were never blessed with instruction, I hope to help here.
First, you need a needle. Before the 20th century, needles were passed on from mothers to children. (We hope to offer old fashioned needles at some point in time. Just need to get the right tool to make them.) Now you can buy very inexpensive needles that you can feel free to lose all over the place, so please get a pair and keep them.
Multi-packs have needles for all sorts of different tasks, but just like the forks at a fancy dinner, there is no reason to panick. If you have a coarse fabric, use a thicker one. If you have a fine fabric, go thinner. If your thread is thick, then the fabric doesn't matter because you need a thicker needle. Thin thread can go into either.
You can thread by looking at the needle or use one of those nifty threaders. In a cheap sewing pack, this will be a thin embossed piece of metal (Looks like an 18th century lady) with a diamond-shaped sprig of metal on one side. Simply poke the sprig through the eye of the needle (The hole opposite the pointy end), insert the thread into the sprig, and then pill the threader back through the other side. Voila. (Warning: You can break the sprig and/or needle if the thread is too thick.)
Later on, I'll post examples of some basic stitches that are very useful for repairs. For now, get to know your needles.