Edmodo is homework/assignments central. There will be weekly online assignments (called quizzes but they're not) due each Friday evening. Edmodo will also be the place to print out new copies of handouts/vocabulary lists/instructions if you lose them.
Remind is for reminding you by text of various things: quizzes, schedule changes, etc. There will be a separate Remind account for parents of Spanish I students in the next couple of weeks.