Good evening!
As for your thesis statement, you could sum it up with something like, "Cultural assimilation is unavoidable when an immigrant moves to America" or "Retaining a pure cultural heritage is not necessary when moving to America"; if I understand your argument correctly.
As far as organization, my advice is to start out with an outline; start in the middle and work your way out. Start with each of these main two to three points you want to touch on. For each point, list a fact or supporting detail, and then an example of it backed by research. When you have your main points and their supports down, then worry about your introduction and conclusion.
I hope this helps you get started.
Regards,
Gloria
Moderator, EssayForum.com
Gloria, EssayForum.com