I'm in Grade 9 and I got low marks on midterm? How to improve?

How will i be able to get all my marks up to around an 85 for the term marks? Help. Tips? I know in grade 9 it's not that bad if you get low marks, but I really want to get higher marks. The midterms are only a way to show you where you are at this point right? Do midterms show up on your file? Or is it just the term marks that will.. If I get high 80's how much will that affect my marks?