You need to get the files onto a computer and then put them onto the iPod. Different MP3 players have different levels of functionality; your best move will be to connect the MP3 player to the device from which you transfered the music that's on it; then, copy those files to the computer that has iTunes,
The process is pretty simple however it does require usb cables and a computer. Simply drag files off of the mp3 player and place them in a folder. Once you are finished connect up the Ipod. Then simply drag the files onto it or use itunes to transfer them. They may need to be converted in a few rare cases.
To transfer videos you need to first connect the MP3 player to your computer. Then, you transfer all the information from the MP3 players onto the computer manually. Next, open up ITunes and import the video files into ITunes. Finally connect the IPod and copy the files onto the IPod