This tutorial will show you how to write php program that can upload any images to your site you can use it as a site for users uploading purposes.Try The Script Here the tutorial
This is a terrible script. The ONLY thing that makes it a bit secure is that you don't put the original extension back to the renamed file, because if you did that, it would be possible to upload .php files and execute them on the server. This makes the usage of this slightly pointless though, because you can't work with the images later on cause you don't know what type they are. Embedding the file without extension may work on some browsers, but it probably won't work on all. And it's really not a good practice. Also, some basic PHP knowledge is lacking too... I don't suggest using this script.