So, in layman's terms, how are we doing HP?

This is my understanding: Your class determines your hit dice, whether that be a d6, d8, or d10. Your constitution bonus determined the additional HP you get for each level. 

So for me, level one= 8+2
Level two= level one hp+ 1d8+2
Level three= level two hp+ 1d8+2

Is that right?