Verb conjugation of "schreiten" in German

Let's not forget how we started. We were writing each other very long messages and today we are both much more fluent in both languages. No book could have brought us that far. Cheers.
Please explain me the exact differences between British and American .... This year I'm trying to make the TOEFL. We can then discuss how we can prepare for this exam. I failed the first time.
My Spanish is weak, and I need to improve it here. But it is very difficult because I have many other things to do. I must take care of my family and my friends and have no time for Spanish.