can and be able

How can I use can and be able in correct way?

Can is used to explain whether we have the ability or not. Secondly, it would be used in relation with our senses like see, hear.
Ex: I can see the kite in the sky.
Ex: I can understand what you say.

Able- should be used to indicate whether we have done a specific task.
Ex: I am able to Click on the Image.
Ex:I was unable to download the page.

But, this distincition is slowly vanishing away.