Use ser to say who you are and where you're from: sóc (I am), ets (you are), és (he/she/it is). Catalan verb endings already show the person, so you normally leave out jo, tu, ell/ella unless you want to stress or contrast them.
Examples
- Sóc de València.
- I'm from Valencia.
- D'on ets?
- Where are you from?
- Ella és professora.
- She is a teacher.
- Com et dius? — Em dic Marta.
- What's your name? — My name is Marta.
The mistake to avoid
Don't put jo in front of every verb (Jo sóc de València sounds like "*I'm* the one from Valencia"); and say Sóc professora, with no article before the job.
Where this fits in
Greetings & introductions, Catalan A1: Say hello, give your name, ask someone else's, and where they're from.