Thank you so much that you taking the time to read my letter, I take great effort to write in English so that you can read and understand what I mean, because I know only a few words.
Thank you so much for taking the time to read my letter, I have to take a huge effort to write in English. For you to read Understand what I mean? Because I know the terminology is not much.
Thank you very much for taking the time to read my letter to you I will take great efforts in writing letters in English for you to read and understand what I mean. Because I know the vocabulary, not much.