A web application with a wizard to add branding or frames to images

I need a simple web script, it asks you to upload a photo, if the dimensions are less than the minimum required it will ask you to upload another photo, if it is bigger it will show an online crop tool to define area you need if you upload the right size then you move to step #2 which is asking you to upload a 2nd image which should also match the size & have at least 50% transparent area in order to merge it on top of the previous image. Then it will show you a preview, with 3 buttons: download final merged picture or choose another layer or another base image.