The conditional perfect tense is constructed by using the conditional form of the irregular verb haber with a past participle:
 

The past participle does not change forms when it is used in the conditional perfect tense.  For example, tú habrías bebido, nosotras habríamos bebido, ellas habrían bebido, etc.  As in English, the Spanish conditional perfect tense is generally used in the result clause of an "if...then" (conditional) sentence:  Si hubiera estudiado más este año, habría sacado mejores notas. (If she had studied harder this year, she would have made better grades).