Pick a color in the color panel (C-panel ).

Clicking in the circle at the top-left chooses a color where the pointer lies. The selected color is displayed in the square at the bottom-right.

In this sample, orange is chosen. You can also make a color using the RGB mixer (three color bars at the top-right) and some other methods.

I drew lines of different colors here.

Dragging in the black and white gradation line at the center of the C-panel, you can change the brightness of the color.

These four lines are drawn using the same color with different brightness, from lighter to darker.

As you see, you can make different looking colors, changing brightness.

Pentips can be selected by Option panel (O-panel ).

You can choose a pentip from the left and change its size by dragging one of the four corners of the panel on the right.
(You can make a perfect circle by dragging a corner with the Shift key down).

Here I drew several lines using different pentips.

Changing appropriate pentips, you can get interesting effects like crayons, and brushes.
These pentips are actually BMP files, which means that you can easily create your own pentips.

Drawing effects can be selected by Palette Panel (P-panel).

The effects can be chosen with the icons above.
From left to right, Pen, Blur, Rub, Stir, Blur 2, Filter Pen, and Eraser .

The picture is a sample; a line is drawn with a regular pen, and then effects were used on it.

From top to buttom, Blur, Rub, Stir, Blur 2, and Eraser.

Frequently used colors can be registered in the P-panel.

Right-clicking in the buttom boxes of the panel will register the color you are currently using. In the sample picture I registered variation of pale pink and orange in the top line.

You can also pick a color by right-clicking in an image opened. (Dropper feature)