how does mass affect weight

More mass -More weight.

weight = mass * gravity and it is measured in Newtons.

When you get your 'weight' from the bathroom scales you are not really getting your weight at all, you are gettting an estimate of your mass!

Here this mathsis fun unit looks quite good :)

http://www.mathsisfun.com/measure/weight-mass.html

Here is a question for you MG, or anyone else who want to answer,  

When would more mass NOT equal more weight?