Get an image software package capable of editing .tga files - if you do not have one then paint.net is free to download.
I have listed the steps below that I take - the ones with # have a corresponding entry on the screenshot to help locate.
Look for a symbol with a different name or similar looking already in WITE2 database then find its GPxxxx/Axxxx number,
Go to it in dat/art/units
Make a copy
Rename the copy to the new ID number for what you are creating in the database
Open the new symbol in your software editing package and magnify to 1000%
Sample the colour of the text #1A 1B
Cut the old text out #2
Use the insert text button (T) set font to size 8 and type in new name for your symbol #3 #4
Trial and error on placing the text to suit your tastes 5
If you are creating something that has no close match then you need to splice other images or hand draw a new image
Save as per below
Gxxxx/Axxxx as relevant file name #6
.tga as type #7
32bit colour #8
flatten if asked
Hope this helps at least a little - gets easier after few goes but unfortunately it doesn't give you the skills of a real graphics artist.
