You will have to have a website for that, a web hosting and you upload files up there so that they are shared.
Another solution, you can configure your PC to be a webserver and share whatever you want to share. You will have to setup the IIS, and get a fixed IP address from your DSL or cable provider, the address which will be typed to access your PC from any computer connected to the internet, and then you will have to make some more configurations in the IIS to manage this.
Beware that if people start connecting to your PC through this fixed IP and start downloading from you, your internet connection will extremely slow down, as those people will use the badwidth you have for downloading whatever they want from your PC.
However, there are some more steps you will have to make to complete the whole configuration, which I can't recall at the moment, but I think guys here can give us a hand and give you the full details, or else, I will get you all the steps from our System Admin at work and post back.