We are going to be using PhotoBucket in this demonstration. So if you don't have a PhotoBucket account this may still give you an idea of what to do to retrieve your image address.
First, Upload the Photo or Image you want to use on your webpage.
When you finish Uploading the photo/image, get the address as provided with the file:
The URL should look like a web address - http://www.photourls.com/pic1.jpg
This is the address to enter into the Image Tag. Click Here to learn how to use the Image Address in an Image Tag.