Learn Romanian: Am câștigat concursul azi.

In the Romanian past tense (Perfect compus), the helper verb am is used for both "I" and "we". So am câștigat can mean "I won" or "we won". Without context or a pronoun like noi (we) or eu (I), it could be either. The translation here shows it means "we" in this particular situation.

If am can mean "I" or "we", shouldn't we add noi to make it clear?

You can say Noi am câștigat to be perfectly clear, but Romanians usually drop the pronoun if the context makes it obvious. You only really need to add noi (we) or eu (I) if there is a risk of confusion or if you want to emphasize exactly who won.

How does the word concursul translate to "the contest"?

In Romanian, the word for "the" attaches to the end of the noun. Here, the base noun is concurs (contest). Because it is a neuter noun, it takes the definite article -ul at the end, becoming concursul (the contest).

I have seen astăzi for "today". Is azi the same thing?

Yes! Azi is just the short form of astăzi. Both mean "today" and are used interchangeably in everyday Romanian, though azi is very common in spoken language because it is quicker to say.