Activate the ‘Selection Tool (V)’ on the left and click to select a shape you have drawn.
Shapes and text can have a ‘Fill’ and a ‘Stroke’ color.
For the shape below, the pink color is the ‘Fill’ and the yellow color is the ‘Stroke’ or border. The ‘Fill’ or ‘Stroke’ can be a color, gradient, or pattern.
There is also an option for mixing or creating your own colors by choosing a location of the color palette. (HINT: If you have the CMYK or RGB data you can input that into the color palette to get an exact color.)
There is also an option to use the ‘Color Picker’ to select a color. You can access this by double clicking the ‘Stroke’ or ‘Fill’ Box in the toolbar on the left. 
Once you do that the dialog box below will pop up. You can use the ‘Color Picker’ to create a custom color visually by entering color values, or by choosing from a library of colors.
Making a custom color in the ‘Color Picker’ does not mean the color is saved to apply to other objects. If you would like to apply the same formatting from one object to another you must either write down the CMYK or RGB data OR use the ‘Eyedropper Tool (I)’. 
In order to make another object the same color you need to activate the ‘Selection Tool’ in the Toolbar and then select the object you would like to change the color of. Once the object is selected activate the ‘Eyedropper Tool (I)’ in the toolbar.
Select the ‘Gradient Tool (G)’ or double click the small gradient box below the ‘Fill’ and ‘Stroke’ boxes in the toolbar to add a gradient to an object. 
Once you have selected to add a gradient a ‘Gradient Panel’ will show up on the artboard or in the panels on the right. 
You can edit the colors of the gradient by double clicking on the white or black circles in the panel.
The diamond above the gradient bar allows you to change the center of the gradient in the object.
