Each candidate needs to be voted upon. If you have three vacancies and three candidates and there is a majority in favour, they are in.
If there are more candidates than vacancies then there is full legal procedure to follow.
We do an informal interview at our staffing committee (open to the public) - to ensure they know what commitment they need to make and our current work, their background, experience etc, then a quick interview at full council with councillors vote at both sessions, this ensures anyone in the public who knows the candidates and has concerns can raise them before councillors vote on them.