How to: Internet connection to router from computer?

So, I have a computer with an internet connection. Is there anyway that I could, using an old router connected to my computer, broadcast the internet connection?
So the connection would go:
Wifi device -> Router -> My computer -> Internet.

Remember, I already have internet on my computer, and their is no way i could get the connection directly on the router. I want to know if there is anyway to transfer the connection through my computer, for the router to use.