How do I deodex my DX / What exactly is deodex?

[royolpunk]

So I've been trying to install new ROMs and themes, but everything says I need to be deodexed. Then, I try to use xUltimate to deodex but whenever I get to Step 3 (Deodex system/app/ etc.) It says file not found. I'm trying to apply themes like these:

[THEME] SenseX 2.2 (BETA) - xda-developers

As you can see it asks for deodex. How can I deodex my DX (running on GummyJAR ROM, Android 2.2.1 2.3.40.) The easiest way possible?
Thanks to anybody who responds

Edit: looks like the theme isn't compatible with 2.2.1 OTA. Anyone can still tell me how to deodex??

[Ads]

[C Dippa]

If you're running a custom ROM, you're probably already deodexed.

Not familiar with that ROM, but check where you got it from and see.

Sent from my DROIDX