netomx , depending on your player's firmware, currently only the v3.5.35, v3.5.37 and v9.0.43 are able to be reskinned.
There a full guide on reskinning here
http://www.mympxplayer.org/how-to-mo...ng-vt1719.html
Be sure to only use your own extracted firmware for reskinning and not other's themed firmwares.
You can download a few theme packs from the downloads section and swap the images individually.