Should I contact an editor at the journal that rejected my paper, to ask for feedback? Recently I got a rejection of my paper from a reputed journal. There were two reviewers who reviewed my paper.However reviewer1 accepted it while reviewer 2 rejected with some suggestions that can be well implemented. The strong reason for the rejection mentioned by the reviewer 2 was the some similarity with my earlier paper. 

My Query 
One of the associate editor of this journal is the well known author working in my field and he has also received the mail notification regarding rejection of my paper. Perhaps he has reviewed this work as well. Shall I contact him to discuss about this rejection and ask for help to further improve our work as per his suggestions. I am fully confused and depressed with this rejection. As I was expecting this paper to be published in that journal. 

I need help and suggestions. It would be of great help if someone could help me 
in such case how to write mail. As English is not my first language I find it hard to write a convincing mail.
No, I don't think you should contact the editor. Journal editors are very busy people, and they don't have time to offer individual comments on every paper.

If you think that your paper did not get a fair review, for example if you have reason to believe the reviewer did not read or understand the paper, then that is worth contacting the editor about. But if you simply want to discuss the paper, the editor will likely view your request as not worth their time. They have already given you their comments on the paper, in the form of a rejection decision: in other words, the editor does not consider your paper appropriate for publication in the journal, and a discussion is not going to change that.

I also think asking for suggestions on how to improve the paper would be inappropriate, because you have already been given suggestions, in referee #2's report. My advice: make the improvements suggested by referee #2 and try submitting the paper to a different journal where it might be a better fit.