Nested IF statments

I would like to do perform a nested if statement but seem to be doing it wrong.

example:

I am asking a question and would like either the answer be y or n. If the answer is not y or n the error message is displayed.

question::

Is the value given?(y/n)

the user will have to input y or n in cell G8, so in H8 I try to include an if staetment:
=IF(G8=y,"Please input the value below",IF(G8=n,"Please proceed with Step 1",IFERROR))

Please send me in the right direction.

Thanks.

Works great!! Now how do I set it so that "Error" is not the default reply? How do I leave cell H8 blank until there is an input?

Thanks again for the help!