Please can someone tell me how national income is increase and how new money is made through trade...?

Question

and other things such as the treasury and the multiplier effect. Please explain in detail as i don't know tons about economics.

Answer 1

This is simple. Think about it this way;

We make $2 worth of goods in the US and sell them for $4 to Europe. We just made $2 or 2x on our money. This way we just brought in an extra $2 into our economy.