In the medieval Roman Catholic Church and among extreme Anabaptists at the time the Confession was written, men forced themselves or were forced upon the churches apart from any input or say on the part of the congregation. No one may force himself and his teachings upon Christ's church. According to the Confession, then, those in church office are to be chosen or elected by the church. We see this in our Scripture reading from Acts 6. It was the congregation of believers, and not the apostles, who chose the seven deacons.
Election is done with prayer.
Election is done with prayer because what the congregation does is confirm the call which comes from Christ Himself. In the London, England church served by the Reformer, John Lasco, a day of prayer and fasting was proclaimed as a fitting preparation for electing those in church office. When a Church Council announces the names of those who are nominated for church office, there is often much kidding about campaign speeches and managers. When I was little we used to play church. We'd get the chairs into rows, fight over who'd be preacher, vigorously lead the hymn singing, and generally have a great time.