Grammatical homework :

Could is used to ask for a permission:

-Could I open the window?

or to tell I was able to do something in the past:

-When I was young I could touch my nose with my foot.

Would is used to express a condition:

-If I was taller, I would try playing basket-ball.

or to ask something in a way more polite than could.

-Please, I would like to rent a car for holidays.

Should is used to give an advice:

-You should come with us! It will be great fun!

-You should listen to the teacher. Or you won’t be able to do your homework!

Is that good?  I’m not sure.