My imovie is not working on my macbook?

After I take a video of me on my imovie, it takes about 30 minutes for a 5 minute video to load. After i click "done" After that it says it is "Analyzing For Stabilization" And it takes a really long time. My teacher in school say I am really good with this app. And I am upset cause it is not working anymore. Is there a simple way u can explain how to fix this? I am 12. But if you tell me to click on certain buttons I can keep up. I am pretty good with it. Please give me step by step instructions! Will choose best answer.