Click on the watch movies link that can be located towards the bottom of this page.
In the search box, type in The "Dear John" and then hit enter.
On the following page, find the link that says Dear John, then click to open it.
Browse for the link option with the highest rating. The higher the rating the more better chance you have of being able to successfully watching the movie, and the higher the quality of the film itself. If you are not satisfied with the link that you try, or it does not work, look for the second highest rated option.