After an initial Google it seemed that this was going to be a lot more complicated than I thought, but in reality the solution is incredibly simple!
- Within your website, create a folder (e.g. named downloads) where you will keep the files that users can download.
- Within your webpage (or ASP.NET page) add a simple anchor tag (that's the <a>... </a> you usually use for links.
- Set the href property to the location of the file to download.
It's that simple - so you should end up with a tag like:
<a href="../Downloads/documentToDownload.doc">Click here to download file!</a>
Clicking this in your page instead of linking to a page will simply start downloading the file in your browser - easy!