1. Make a new image. It has to be at least 500x500 with a white background.
2. Select the text tool and any font/size that you want. Make sure floating and anti-alias are checked.
Your image should look like this:
3. Go to Selections -> Modify -> Feather and set the Feather to 5.
4. Take the flood fill tool and click on the text. It should come out like this: