The future tense is used to tell what "will" happen, or what "shall" happen.

I will go to the beach next month.
I shall write the letter next week.

Regular verbs in the future tense are conjugated by adding the following endings to the infinitive form of the verb: -é, -ás, -á, -emos, -éis, -án.

hablaré
hablarás
hablará
hablaremos
hablaréis
hablarán

Also note: 

The future tense is also used to express wonder or probability in the present state.

¿Quién será ella?
I wonder who she is? (Who could she be?)

Estará viajando solo.
He is probably traveling alone.

For actions that will occur in the near future, the present tense is more commonly used.

Esta noche voy al cine.
Tonight I'm going to the movies.

Further in the future, use the future tense.

El año que viene iré a España.
Next year I'm going to Spain.

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Irregulars

There are twelve common verbs that are irregular in the future tense. Their endings are regular, but their stems change. Since the endings are the same as all other future tense verbs, we show only the "yo" form, and have underlined the irregular stem. We have also grouped them according to their patterns of change.
caber
yo cabré
poner
yo pondré
decir
yo diré
haber
yo habré
salir
yo saldré
hacer
yo haré
poder
yo podré
tener
yo tendré
querer
yo querré
valer
yo valdré
saber
yo sabré
venir
yo vendré

Modified from the original at StudySpanish.com