Present Perfect already, yet, ever, before and never

Use before to talk about life experiences.

place it at the end of the sentence.

Use it in Yes/No Questions and affirmative senteces

Have you been in Ometepe Island before?

I have been in Ometepe Island before.

Use ever to talk about life experiences

place it after the auxiliary(have) in negative sentences and after the subject in questions.

Use it in negative and questions

Have you ever tried Korean Food?

I haven't ever tried Korean Food.

Use never  in negative sentences and short answers 

I have never been in Costa Rica.

Have you ever been in Costa Rica?
No, I never have.

Use already in yes/no questions and affirmative sentences to talk about recent experiences.

Has she already taken a tour of Mombacho Volcano?

She has already taken a tour of Mombacho Volcano.

Use yet in yes/no questions and negative sentences about recent activities

place "yet" at the end of the sentences

Have you climbed a mountain yet?

I haven't climbed a mountain yet.