Once you have Any Video Converter installed, you can start converting your files.
You can convert your videos to a wide range of formats from the program's drop-down list on the upper right under "Profile."
If you want to have a file that will work on just about every player out there, your best bet is to convert your file to the MPEG-4 format, also known as MP4. MP4 is like the de facto format for portable video players. It's supported by the iPod/iPhone/iPad line, the G1 "Google Phone," PSP, and a host of other portable devices that play video.
From the drop down list, pick "Customized MP4 Movie."