Your marriage certificate will generally get apostilled by the state that issued it.
From what I recall FBI and marriage were the only two we had to get apostille for. There are also businesses that help complete this process quickly if you’re finding it confusing to navigate yourself. We used Monument Visa.
If you have children on your application I believe their birth certificates are also required. Birth certificates also to the state’s secretary of state which issued the document. There may be others depending on your situation so obviously consult your attorney if you are using one.
Note that you also need to have the document and apostille translated into Portuguese. I used an online company and it was very cost efficient.