The electors who technically select the president are chosen in a variety of ways. There is no one set way that must be followed. Instead, each state is free to set up its own system for selecting electors.
Typically, the way this works is that the parties select the electors who would vote for that party's candidate. The electors are generally party activists in that particular state. They are chosen at party conventions or in other party meetings.
Electors, then, can be pretty much anyone who a party wants. The only real restriction is that they cannot be officials of the federal government.
The electors of the Electoral College are real people. How they are selected is determined by both state law and the rules of the political parties.
According to the U.S. Office of the Federal Register, "Generally, the political parties nominate electors at their State party conventions or by a vote of the party's central committee in each State. Electors are often selected to recognize their service and dedication to their political party.They may be State elected officials, party leaders, or persons who have a personal or political affiliation with the Presidential candidate. Then the voters in each State choose the electors on the day of the general election. The electors' names may or may not appear on the ballot below the name of the candidates running for President, depending on the procedure in each State."