For life experiences ("I have done X" at some unspecified time), use the present tense of haber - he, has, ha, hemos, habéis, han - plus the past participle, which you make by swapping the infinitive ending for -ado on -ar verbs and -ido on -er/-ir verbs. It pairs with alguna vez, nunca, ya, todavía no and muchas veces, unlike the preterite, which needs a finished time marker like ayer.
Examples
- ¿Has estado alguna vez en Argentina?
- Have you ever been to Argentina?
- Nunca he probado el ceviche.
- I have never tried ceviche.
- Ya hemos visitado el museo.
- We have already visited the museum.
- Todavía no he visto esa película.
- I haven't seen that film yet.
The mistake to avoid
The participle never changes for gender or number, and nothing may come between haber and it - say "nunca he visitado", not "he nunca visitado" or "he visitada".
Where this fits in
Talking about the past, Spanish A2: Tell stories about yesterday, last weekend, and life experiences. Preterite for finished actions, and 'haber' + participle for life experiences.