We all have to start off somewhere.
So I’m going to subvert the very nature of that question. EVERYONE can write. You might not be experienced at writing. It might not be a skill that you have polished or honed. But if you’re looking for footage or just to get started the way you learn is by practicing.
If you can act, you can communicate. If you can communicate then you can write. Start by transcribing an improvisational conversation between you and one other person. Place that conversation in a relatable setting. Have it make sense and play a character that is very close to who you are in real life. Then shoot what you have written. Boom!
You can also buy my books. The Funniest Scenes in the World, Volumes 1 and 2 were written exactly to solve that problem!