In Italian, we have to ways to express the verb to be: verbo essere e verbo stare. I am going to write the present tense of the verb to be in English and then in Italian.
I am, you are, he/she/it is, we are, you are, they are (presente simple of the verb to be)
Io sono, tu sei, lui/lei è, noi siamo voi siete, loro sono (presente indicativo del verbo essere)
Io sto, tu stai, lui/lei sta, noi stiamo, voi state, loro stanno (presente indicativo del verbo stare)
For what concern the past, in English you have the past simple, the presente perfect. and the present perfect continuous) I will write the past of the verb to be, but the same works for other verbs.
I was, you were, he/she/it was, we were, you were, they were (past simple)
I have been, you have been, he/she/it has been, we have been, you have been, they have been (present perfect).
In Italian, we can traslate these two tenses into three different tenses: indicativo imperfetto del verbo essere, passato prossimo del verbo essere, passato remoto del verbo essere
Io ero, tu eri, lui/lei era, noi eravamo, voi eravate, loro erano (imperfetto)
Io sono stato, tu sei stato, lui/lei è stato, noi siamo stati, voi siete stato, loro sono stati (passato prossimo)
Io fui, tu fosti, lui/lei fu, noi fummo, voi foste, loro furono (passato remoto)
I have not mentioned the usage of the three and I have not mentioned the subjunctive and other tenses, but to give you an overview, you need to know that the verb to be in English has two forms in Italian, and that the past in English (past simple, present perfect and present perfect continuous that I have no mentioned) has three main tenses in Italian (passato prossimo, imperfetto and passato remoto).
I hope this answer can be of some help!
Good luck on your Italian.