This is my feble attempt to write a tutorial on how to flood fill a hollow font for
psp beginners.  I am not good at tutorials for PSP beginners.  AND I don't
use psp7 any longer and haven't since PSP 8 came out so I stumble using it
because PSP 8 is so much simpler.  I have to relearn PSP7 every time I use it.
Hopefully if you have some basic knowledge of PSP you will be able to follow this tutorial.

Open a new image in psp (blank canvas)
by clicking on file/new and choosing a size for your new image

O

Click on the font icon  then click on your blank canvas where you want your text.

The font box will open as below.  Depending on the font you are using you may only need the outline color.  If you are
using a hollow font choose both colors so your outline will be solid and not hollow.
example is pc balloons seen below.  Set your font size to at least 100, I used 150 in psp7, be sure you have the floating box checked
and the antialis box checked. Type the letter you want to flood fill

Click ok to go back to your canvas with the A in it.  Click on Selections/Select none.  The marching ants will be gone
from around your letter.

Now click on the magic wand  and click inside the hollow letter.
BE sure the feather is set to 0.  The center of you letter will have marching ants in it.  Bo to selections
Modify, Expand and choose to expand by 1
 

Now click on the flood fill (bucket) 
Choose the color from the TOP box on the color palette that you want to fill the letter with.

Now click on selection, select none to get rid of the marching ants.  You can crop the image with
the crop tool   to crop around the image
to get ride of extra space.
or you can use the scissors  to simply Cut the
letter out of the canvas. The right click on the work area of PSP and choose paste as new image.