Your introduction should probably be around 1 – 1.5 pages in length. Basically, here you summarize IN YOUR OWN WORDS the material in the introduction to the exercise. This is the best place to get in your references to primary literature too. You may want to briefly talk about the history of cloning. I highly recommend looking up terms, such as cloning methods and uses, on Wikipedia, and then using the references in that article (you must actually go to the referenced literature and read it though). 

I attached the lab manual it will be on exersice 3 and 4