Why did england want to begin a colony on northamerica eastern shore

Is your question why not on the western shore? They didn't have access to it, Japan and China would be able to, as they had better access to it. But England would have to go through the Arctic ocean or Asia to access the western shore first. 

Why in America? Because America was a newly discovered continent with weak defense, it was the easiest place to establish a colony.

And they wanted a colony because it meant an increase in wealth and power.