Multiplying polynomial is just like multiplying numbers, (e.g. 9x9), only that you have to multiply each term on the other, then add similar terms. You must also consider the laws of exponent for your variables. Example is (2x+1) (2x+2) =  4x^{2} + 6x +2 .

And, you can also use special products and FOIL Method.
 Here is a picture of my notes about special Products, you can refer to it (much better if you can memorize it).

Enjoy doing homework :)

First multiply the numerical coefficient then multiply the literal coefficient by applying the laws of exponet