I would think that the web site "hosts" files (like pictures) that others could direct link to (like what members here have to do when posting pictures).

Your question is really very vague, but I guess you are asking what a host does for you. Its simple, they offer space on their servers to store and display graphics and or websites. Most charge for the service by the month depending on the amount of service you require, but there are still a few out there that are free. Each have their own set of rules as far as the amount of data you can store, how much bandwidth you can use and if linking outside their server is allowed. There are different types of host from "full service" to just photo and graphic storage. Full service are general the ones that charge where you can host your websites and might include a domain name, email and other services. Photo and graphic hosts do just that, let you store your stuff on their servers for viewing on the internet, but not all allow linking to places like here on the Garden Web.

If you are looking for a free service you need to google, but besure to read each ones TOS (Terms of Service) before signing up. You also might check with your ISP as most of them offer free storage. There again besure to read the TOS!

If you want to play around with one of the free ones, check into Angelfire/Lycos....

They have "advanced" options as well for HTML authoring.

If you do decide to begin paying for webhosting at some place like GoDaddy or other, you can easily transfer your files from and to if you have an FTP application.