Grid-Help(I think iam using css grid in wrong way)

Hi everyone I started using grid layout but now i think iam using it wrong way.Kindly see my code.
codepen is

I’m not sure what you’re trying to do. Maybe, start a bit simpler.

Thanks, this is a most awaited me ,i learned grid and started making small layouts, in codepen that was small medium website layout but iam doing it wrong way. could you help ,what is the first step of making layout? should i count how many boxes are there and then how many div i want ,should it be equal to no of boxes , iam uploading a pic ,just tell me how should i start.again thanks for reply.