To say what's happening right now, Portuguese works much like English be + -ing: a form of estar plus the gerúndio, the -ndo form of the verb.

Eu estou falando com a Luana. — I'm talking to Luana.

To make the gerúndio, take the infinitive, drop the final -r and add -ndo:

Infinitive	Gerúndio	English
falar	falando	speaking
comer	comendo	eating
abrir	abrindo	opening

So it's -ando, -endo or -indo, depending on the verb family. Two things make this easy:

• Only estar changes for the person. The gerúndio never changes — no gender, no plural: a Luana está comendo, os meninos estão comendo.
• Nearly every verb follows the rule, even the irregular ones: ser → sendo, ter → tendo, estar → estando.