Help! acl and meniscus tear, focal edema, and joint effusion.?

ok so i finally got my diagnosis for knee. i have a torn ACL and torn Meniscus, my doctor said that i will have to replace my acl but didnt say much about my meniscus. I was just wondering what exactly they do and how they repair a torn meniscus. i know that my doctor (family doctor, arthroscopic surgeon, and physical therapy doctor) all have said that because of my age and my activity level it will be more urgent and i cant really find an information on it. anything would be greatly appricated. oh and my MRI said i have a small joint effusion, and focal edema within the subcutaneous tissues anterior to the patella. Honestly at age 14 i have no idea what this means, i'm looking online but it's not really telling me anything. please help. i'm really uncomfortable going into surgery not having a complete understanding of what is going on. anything is appricated. thanks. :]