There are a lot of choices there. The top row contains a number of blocks for which colors can be selecting with the right click menu. You can select a different block when you change colors, then the previous colors are preserved for you to go back to without having to select them again. The block which has a black edge around it is the one that is selected. You can also choose pure white or black.
Textures are another option.
The Magic Texture and Natural Texture libraries come with PhotoImpact. Click on these and browse through the selections, there are a lot of them and as you will see later, you can change the color of any of them after you apply them. This is the Fill Menu in PI 4. You can select a portion of a picture and use it as is or make it into a tile with a filter, or use a separate texture that you have gotten somewhere. Below is a nice textured tile that makes a lovely background to paste a picture onto.