Go the Wall Properties, on the Trim tab, go to Custom and choose Wainscot. Do this on the side of the wall where you need the tiles. You can determine which side of the wall is Left or Right by looking at the colour of the wall end markers. You originally drew the wall from the Green dot to the Red dot. Imagine you are standing on the green dot facing the red one, the left and right side are then obvious.
The Wainscot is in effect a panel that attaches to the wall (eg Tiles). You set the height and what tile or texture you want and how thick it is and it is applied to the bottom part of the wall.
Hope that is clear enough for you to find it.