Let me see if I can help out with what you need to do.
1. Save the Dueces Wild sig to your computer, somewhere you may find it easily. (I usually save that kind of stuff to my Desktop to start, then move it when I'm done.)
2. Edit it however you would like it, and save it back to the same location you originally did.
3. Go to the Gallery
4. Click the "Upload Photos" button.
5. From there it will ask you which gallery you'd like to save it in. Leave this the same.
6. There will be multiple slots with a "Browse" button beside it. Select browse in *THE FIRST BOX, and find the file where you saved it.
7. Click the upload button of course, and go through the rest of the gallery as it asks until your file is uploaded.
8. You should then be taken to your gallery. Click the thumbnail of your sig.
9. Now you should have the full sig in front of you. Scroll down until you find the 
10. Copy this, and goto Edit Signature
11. Paste the [img] info into the edit box, and click save signature.
If you did that, then you should be fine.