When someone wants to become President, what must this person do first? Meet the Constitutional requirements (age, residency, citizenship). Get people to vote for them at the primaries.

Correct, to become President, a person must first meet the Constitutional requirements, including age, residency, and citizenship. After that, they typically engage in the political process, including participating in primaries to secure the nomination of their political party and ultimately gaining the support of the electorate in the general election.