Have you travelled to any country in Europe?
Yes, I have been to Portugal.
So if you don't specify a time you should use the perfect tense.
Today I am going to Portugal (present continuous tense)
Yesterday (or specific time in the past eg last May, or in 2011 or last week) I went to Portugal (past tense)
I have been to Portugal (sometime in the past not specified) (perfect tense)
I will go to Portugal (future tense)