Traditionally there are 4 candles to the advent wreath. They can either be all white or 3 purple and one pink.
Some have 5 candles, the 5th candle is just used to light the other candles.
A new candle is lit for each of the 4 Sundays in Advent. If you are using the 3 purple and 1 pink candle, the pink candle is used on the 3rd Sunday of Advent.
When you light the candles and what you do when the candles are lite is up to you. I tend to do my daily readings and the Liturgy of the Hours Morning and Night Prayer with the candles lite.
Usually closer to Advent, EWTN’s web site will list blessings and prayers that can be used with advent wreaths, nativity scenes, and Christmas trees.