Paste an image into specific shape

[Giffin]

Hi Everyone,

I'm looking to take a picture of a flag and paste it into a specific area of another photo.

So I have two pictures:  One of the flag and the second one of a tractor in a field.  The tractor has two large wheels.

I'm trying to take the entire flag and paste it into each whee seamlessly.  The flag will be a bit distorted as it takes the shape of the wheels, but that's okay.

Is there an easy way to do this?  

Can anyone provide the steps?

Thank you

Giffin