Clicking on the   text tool on the tool panel brings up the Text panel.  With it, you can add text in various styles to your picture.

You also get a box that you can enter text into on your buffer.

This box can be moved around or re-sized by clicking and dragging on its border.  The mouse pointer will change shape to indicate which action will take place, depending on where on the border you click.

You can also reposition the box anywhere on the buffer simple by dragging the mouse around while this tool is active.

Note that keyboard shortcuts will be swallowed by this tool, so you'll have to switch tools if you need to use a keyboard shortcut.

The “Apply text” button applies the text as it exists in the edit box to your buffer.  Settings on the panel will effect its final look.

Show textbox will redisplay the textbox if it is invisible.  This will happen after you have entered text.  You can press this button to get it back if you want to add more text.

This row of buttons lets you format the way your text will look.

Pressing the font button brings up a system dialog box to select a font.  See the Font Dialog below.

The remaining tools set the alignment of your text inside the text box.  There is left, center, and right alignment.

The Font panel lets you select a font for your text.

The list on the right lets you select from any font that is installed on your system, like these...

Arial
Times New Roman
Courier

The font style list lets you select a style like Bold, Italic, or Both.

The Size drop slider lets you select the size of your font, like  14   18   26

The area at the left, bottom shows a preview of text using the font:

A quick brown dog

The text box in the top, next to the magnifying glass icon lets you search for a specific font by name.

This settings let you change the way your text is rendered when you apply the text.

The Plain text mode renders the text using the current primary color.  The current brushes opacity is not taken into account.  If you have anti-aliasing turned on for the system font, it will be taken into account, causing your font to render more smoothly.

The Use fill settings mode renders the text using all of the current fill settings.  For example, you can use paper textures, gradients, transparency, brush warping, and anything else you can apply to a fill tool.

Text to alpha causes the text to be rendered to the alpha channel, effectively making a 'selection' in the shape of your text.  You could then use this to paint into, or to apply effects to.

These tools effect the placement of your text box inside your buffer.  The arrow button nudge the box by one pixel in any direction.

Center horizontal and Center vertical will center your text box in the buffer.

These tools will make a custom brush out of the contents of your text box.  The brush will be rendered in any of the styles (above)

Make animated will cause an animated brush to be created, with one character from your text making up a single frame.  With the complete animated brush, you will be able to draw with your text in a free-form fashion.