How can I get my itune songs onto bush MP3 player

You can't do it via iTunes. If the music is downloaded into your iTunes library then it's already stored on the laptop - to see where they are stored right-click (control-click on Mac) a track in the Music section of your iTunes and select 'show in Explorer' ('Show in Finder' on a Mac).

If the songs are iTunes purchases you might have to convert them into a compatible format before you can copy them to your MP3 player e.g. Convert a song to a different file format with iTunes - Apple Support

Connect the player via USB and drag-n-drop the MP3s into it.

iTunes cannot sync it the way it syncs an iPod. However, you can use the same MP3s that you also use with iTunes.

For more details, see the online manual here:

http://portablemedia.manualsonline.com/manuals/mfg/bush/mpk4099buk.html