You use an <input type="file"> on a web page.
Your form has to have the following attributes:
method="post"
enctype="multipart/form-data"
For the server end of things it is easiest to use a pre-written library.
Recommended libraries:
- [url http://jakarta.apache.org/commons/fileupload] Commons Fileupload[/url]
- [url http://www.servlets.com/cos/]com.oreilly.servlet[/url]