Check out istockphoto.com and shutterstock.com. There are many other websites which allow people to create logins, and sell stock footage. However, good websites - as in - with good traffic and good sales and good revenue models will most often have a very strict criteria for curating your footage.
Once it is approved, it is available for sale via these websites, you get a % of revenue from each download.
There are many other things, like the model of purchase (cash/credit points), or share (direct % or certain amount after x downloads) which are website specific and can be complicated to understand. You'll have to do your bit of research.