The GP-10 has 99 patch locations available.  From the factory, all 99 patches are already filled with Roland created patches, but each of them can be edited however you like. Once you've edited a patch, you can store it into any of the 99 locations. Here's how: 

1. Edit the patch as desired. 

2. Press the WRITE button. "Write to" appears in the display. 

3. Turn the PATCH/VALUE knob to choose the location that you want to store the patch to (1-99). 

4. Press WRITE. 

5. Use the PATCH/VALUE knob and the parameter < / > buttons to custom name your patch. 

6. Press WRITE. 

The new patch is now stored in the location you chose in Step 3 above.