Add a file upload mechanism

I have an existing website that I want to add a file upload mechanism where users can populate a small form that includes first name, last name, email, and the ability to upload up to 50 image files with corresponding captions. This mechanism needs to be secure! The script will move the images from the temp directory to a directory that is named after the user's last name (maybe with a digit appended to make it unique). Then the script will create a simple html page within the same directory to display those images.