Hello Jaimu, how are you! Nice to know that you are coming to Portugal! We have 3 airports, Oporto - (if you want to visit the north of Portugal), Lisbon, anda Faro (south)
If you wanna go to the Algarve, were the beaches are, you should land in Faro, on the other hand, if you wanna go to the capital, Lisbon international airport is the best choice!
Just let me know if you need more informations! :)