How do you do it from your computer? Don't.
You'd be an idiot for setting one up. Why? Because all US ISP's disallow it.
Now, as for what Dynash says: Yea, you can test a setup and such and put it on another server. But, a home/residential internet connection will be terminated if it stays as a home file server for other users. And another why? Because you aren't allowed to have multiple incoming connections to your home. You can have as many as you want going out, but only a few coming in.
But, I'd be glad to help you setup a file host on your computer if you want.