How do American political parties nominate presidential candidates?

There is a series of primary elections held in the states, followed by a national convention for each party held at different places each time. The primaries commit a certain number of delegates to vote for the winner of their primary on the first ballot, but after that, they can vote however they wish. Not all of the states have primaries and there are some super-delegates , such as congressmen and such that are independent of primary results. The final, official nominations are made at the national conventions.