I have a Midwest spa sub panel does the feed from main box hook to the lug under the nutarel bar or to the bar its self

Please try your question again. This is impossible to understand.
What is "the bar its self"?

Is this the panelboard that you want us to guess about? If you look at the instructions that come with the panelboard they will guide you. If you cannot read and understand the directions, then get a licensed electrician to do the work before you accidently kill someone.

Electricity and water do not play well together.