Hi new to the forum and new car but having some issues

I need to replace the fuel return pipe but i cannot get the pipe split from the front of the engine. It looks the same as a fuel filter type fitting but it wont come away. Could someone tell me how it comes off as i have tried all ways but cannot get it to shift

here is the pic, its the white connector, please help cos im looking at the cutting gear fondly lol

[IMG]http://i1103.photobucket.com/albums/g464/onqmusic/DSCN1363.jpg[/IMG]