Put in a ponytail. Then, wrap your hair around the center and tie an elastic around the bun. If you want a neat one, use lots of clips to keep it in place. If you want it curly, add a lot of hair ties on it to make it hold together. It takes practice. Good luck!
I have these twisted bobby pins that you can find in most style stores, and they work really well. It really depends on your hair. It is more difficult with really thin hair or really thick. The way I do mine, is I put my hair up in a ponytail in the place I want it. Then I bring my hair up and wrap it into the style bun you want, then twist the "twisted bobby pins" into the hair, then pin any remaining hair up with normal bobby pins. Also, I use a LOT of hairspray.
You can find tutorial videos online, and those really help. You could also ask your hair stylist, friend, mother, aunt, grandmother, etc. for help.
Hope this helps! Good luck!
P.S. Here is the link to find the "twisted bobby pins". It includes a picture and description.