Hi and welcome to the forums.

I'm a bit farther north - in France - but I assume by "work contract" that they mean you need to have a job offer, with a copy of the contract they are offering you (i.e. terms of the job, salary level, and whether this is a "permanent" job or a term contract).

Finding a job in Portugal can take some time, especially from outside the country. It will also depend on your line of work. Have you done any looking so far on your own? You could try some international job posting board (Monster et al) or see if you can find the online sites for some of the Portuguese newspapers that post job ads, though often those are aimed at locals with work privileges already in hand.

We have a few members who are currently in Portugal and should be able to point you in the right direction.
Cheers,
Bev