Here's a good starter website for learning what FPGAs do, how they work, etc., with some simple example designs and links to more resources. If you want to learn about image processing or video processing, you should search the web for basic information. Xilinx and others offer FPGA development boards with example designs for video processing, including video input and output ports.
VHDL is a design language. Before you start writing design details in VHDL, you need to figure out what your design is.
Writing down the notes on a page of blank sheet music isn't the same thing as composing.
-- Bob Elkind
SIGNATURE: README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369
Summary: 1. Read the manual or user guide. Have you read the manual? Can you find the manual? 2. Search the forums (and search the web) for similar topics. 3. Do not post the same question on multiple forums. 4. Do not post a new topic or question on someone else's thread, start a new thread! 5. Students: Copying code is not the same as learning to design. 6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please). 7. You are not charged extra fees for comments in your code. 8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.