First you need an account. If you haven't already created an account, go here and create one. The only fields you need are a nick and a password. Of course, you are free to enter any other information you wish and upload a picture.

You'll also need webcam software. There are a couple of ways you can go about doing this. You can either ftp your image up to a webserver somewhere and serve the image from there, or run a webcam program locally with a built in webserver to serve it locally.

Running it locally:

Advantages:
The updates are fast. The images will update on the client side as quickly as possible and will scale down as the load increases. If you have a 256kbps upstream and one person is watching, they would get about 5 frames per second. If 5 people are watching, each one would get about 1 frame per second.

Disadvantages:
Your provider may not permit this, since it involves running a local server. Check your ISP's Terms of Service to see if this would be in violation.
If you are running a firewall and/or a router, you may need to do some configuration to forward the chosen cam port so it can be accessed from the outside world. Some knowledge of the software and hardware you're using will be necessary.

Using a remote FTP/Web server:

Advantages:
Easy to configure.
Minimal bandwidth requirements. The bandwidth hit is taken by the network hosting your image, not your connection.
No concerns about TOS violations

Disadvantages:
The updates are slow. You're not likely to get better than 1 frame every 3-5 seconds no matter how fast your connection might be.
You'll have to find an ftp/web server. Likely you can find one for free, but I have no idea where.

You'll need some webcam software. Some choices:

For windows:

Webcam32
Webcam 2000
Dorgem

For Linux:

Camserv

If you know of any good free webcam packages, let me know and I'll add them to this list.

Install your webcam software and set up a single frame tcp/ip server port or configure your ftp account. Once you're done with that, you can log in here