How to submit a patch file?

[wackamole]

I made a change to map.cpp. There are now 2 concentric circles around the player. The circles around the player now scale with the zoom of the map. The inner circle is the approximate spell distance. Works very nice when quadding those beasts in burning woods. :D

Anyway, I tried using the "Patch" item on the web page to submit. Is this the correct way to do it?