Evaporation is a complex concept, but you can help your child notice evidence of evaporation and condensation of water as they occur in your daily routines.
The summer is a great time to observe evaporation outside after a rain shower. Use some chalk to trace puddles on the pavement and then observe frequently over the next hour or two (depending on how hot it is outside) to see what happens. Where did the water go?
In the winter, place some bowls of water around the house to moisten the air and put your child in charge of telling you when it's time to refill them. Draw a line at the surface of the water to mark the level. Your child will learn something about evaporation and you will keep the dry air at bay!
Condensation can be observed in nature as dew on the grass in the early morning. You can create condensation by simply leaving a glass of ice cold water sitting out and observing the drops of water that form on the sides of the glass.
It's not important that you or your child understand the physical changes that underlie what's happening to the water. It's more important to help your child notice and think about these transformations; what's her idea about what happened?