The best place to start for info for Portugal is the Guide to Lisbon & resources.

Marriage is a bit more specific. What are you looking for exactly? FUll regulations can be found on this pdf: http://ec.europa.eu/civiljustice/news/docs/study_public_docs_portugal.pdf

Basics:

Both civil and church marriages are valid in Portugal. Civil marriages are performed and registered at Conservatoria do Registo Civil (Civil Registries). You need to use the one which services the area in which you reside.

The Portugal Civil Registry Code has specific requirements you must meet in order to be married in Portugal. One of you must be in Portugal for a minimum of thirty (30) days before notice of your intended marriage can be given.

Visitors to Portugal must show their passports. U.S. citizens permanently residing in Portugal need to show their residence card. You both need to provide a certified copy of your birth certificates. These certified copies must have been issued within the last six months. ( If your wedding is to take place in the Azores, the certified birth certificate must have been issued within the last three months. ) You also need to provide a Certificate of "No Impediment". The authorities may also require a consular Certificate which is based on your registration at the Consular section. If you want to be married in a Roman Catholic Church, you will need to provide your Baptismal certificates. After you have received approval to get married, your wedding must take place within three months.

All documents must be translated into Portuguese and authenticated by a Portuguese notary public. The U.S. Embassy does not provide this service, but they can give you a list of translators.

License Certification:
Don't leave Portugal without having your Portuguese marriage documents certified at the Procuradoria Geral da Republica, Rua Escola Politecnica, No. 140, Lisboa.

Check the Registo Civil site (http://www.irn.mj.pt/sections/inicio/) for fees and regional requirements.

I hope that helps, but please ask if you have more specific questions.

 

What questions do you have exactly? Maybe it is best for you to go to an immigration lawyer if these resources aren't clear enough. Please feel free to share your experience with the forum as it could be helpful to other expats. Best of luck