-To be
A) How is it formed?
B) When is it used?

It is used as the main verb:
I’ m tired. [Sono stanco.]

Are you English? [Sei inglese?]

Apart from its use as an auxiliary to form both the Present Continuous (see Unit 2) and the Passive, it has its own independent meaning:
I’m from Sicily. [Sono dalla Sicilia.]

He isn’t interested in archeology. [Non è interessato in archeologia.]

Aren’t they late? [Non sono in ritardo?]

Compared to Italian the verb to be has special idiomatic meanings in English:
I’m hungry. [Ho fame.]

I’m thirsty. [Ho sete.]

I’m right/wrong. [Ho ragione/torto.]

I’m 16/years old etc. [Ho 16 anni.]

I’m well. [Sto bene.]

What time is it? [Che ora sono?]

I’m in a hurry! [Ho fretta!]

It’s cloudy/hot/cold/misty/windy etc… [E’ nuvoloso/caldo/freddo/c’è nebbia/vento ecc...]

-To Have
A) How is it formed?
B) When is it used?

1) To indicate possession together with got:
I’ve got a new bike. [Ho una bici nuova.]

Have you got an Apple computer? [Hai un computer Apple?]

I haven’t got enough money. [Non ho abbastanza soldi.]

When have means possession we never use the -ing form.

But in A.Eng. have is used without got to mean possession:
Do you have a light? [Hai da accendere?]

I don’ t have a big family. [Non ho una grande famiglia.]

I’ve an interesting idea! [Ho un’idea interessante!]

it is used as an auxiliary verb with the Present Perfect and in other compound forms:
I’ve always studied English. [Studio inglese da sempre.]

it is also used as a normal verb without got and with do/does with a variety of meanings:
I have a shower before going to school. [Mi faccio la doccia prima di andare a scuola.]

Do you have breakfast before leaving? [Fai colazione prima di partire?]

He doesn’t have a snack at school. [Non fa lo spuntino a scuola.]

have + to + base form is also used to express obligation:
I have to surf the net now. [Devo navigare su internet ora.]

have + got + to is also used in this sense in colloquial English:
I’ve got to do my homework this evening. [Devo fare i miei compiti stasera.]

(see Unit on modals for the different meanings of have in the negative/interrogative forms)
Remember that in the Past forms of have we never use got.
I didn’t have any money yesterday. [Non avevo soldi ieri.]