How to use and conjugate the perfect tense.

The perfect tense is used frequently in both English and Spanish to express completed actions in the past. It is formed with the auxillary verb "to have" and the past participle of the verb that has been completed. In English we use the verb "to have" for possession (I have ten pounds) aswell as as an auxillary verb in perfect tense (I have been to Spain), whereas in Spanish these are two seperate verbs. Tener is used for possession (tengo diez euros), and haber is used to form perfect tense.

In order to form the present perfect tense, we must conjugate haber in the present tense depending on the subject, followed by the past participle of the verb that has been completed, which doesn't change depending on the subject.

Haber: (yo) He; (tu) Has; (el/ella/Ud.) Ha; (nosotros) Hemos; (vosotros) Habéis; (ellos/ellas/Uds.) Han.

+  Past Participle: eg   Ir  ----> Ido;   Comer ----> Comido;   Bailar ----> Bailado;   Hacer ----> Hecho.

I have eaten chicken  ----> He comido pollo;      Have you danced Tango?  ---->  ¿Has bailado Tango?; 

They have been to Madrid  ----> Han ido a Madrid.

Though the formation of the past participle generally follows the rule of removing the verb ending (ar/er/ir) and replace it with ado (for -ar verbs) or ido (for -er/-ir verbs)  there are many irregular verbs (especially ones that are used commonly). This formation is also used for other perfect tenses, such as plusperfect, future perfect, conditional perfect and subjunctive perfect, by just changing the tense haber is conjugated into.