You can fill an object with a linear gradient.
Select the object(s) you want to fill.
Click the Edit button in the fill area of the editing panel.
You will see the Fill Options.
Click the Linear Gradient radio button.
The selection will fill with a gradient.
Gradients include two colors by default. You can have up to 10 colors in a gradient.
Use the Number of Colors slider to select how many colors you want in the gradient.
Click each color box to select a new color. You may also double-click each color box to see a color dialog.
Select a color from the palette.
You will see the selection change.
Use the Opacity slider for each color to determine how opaque that color is.
If you want the linear gradient to cycle over and over, check the Repeating Gradient box.
When you are finished editing the gradient, click the Go Back button on the editing panel.