Create a webapp which has two sections.
Section 1 : You can upload any valid pic(JPG/PNG), pdf or word doc only with limit 2MB.
Section 2 : Here you can see the listing of all your documents. (URL only)
Technology stack : Spring MVC Hibernate MySQL : A table which consists all the generated S3 URLs AWS S3 : All the documents will be uploaded on this server and there is a specific public URL of it. Don't forget client and server side validation. Don't focus too much on UI part, simple bootstrap would be enough. Focus on functionality.
Help http://docs.aws.amazon.com/AmazonS3/latest/UG/Welcome.html
S3 Test Credentials Access Key ID: XXXXX Secret Access Key: XXXXXX