Need some starting help for SE theming?
Then don't hesitate to grab the SE theming kit for SE 4.6, 4.7, 4.8 and 4.9 phones with a 240x320 px screen.

It contains Photoshop templates for the main screens (including the Media Player and Media Gallery) which may be helpful for sketching your theme. Also included: PSD files as placeholders for all single theme elements in order of their appearance in the Themes Creator as well as a „Before_you_start“ .png. Please read the latter carefully.
The latest version of the
Sony Ericsson Themes Creator tool can be downloaded
here.
To skin an SE phones' Media Player Background, you need the
Media Player Skinner tool.
The accordant download link and a tutorial can be found
here.
Happy theming!