Hide / Add / Replace dock icons on home screen
This functionality isn't available as standard in your default launcher, but the launcher is replaceable.  There are lots of alternatives out there, some require a minimum OS version.  Unless you've rooted your phone it looks like the maximum OS version you can be on is v2.3.5 (Source: http://www.gsmarena.com/samsung_galaxy_y_s5360-4117.php).  So this rules out the newer breed of launchers which are based on the Android 4.x launcher.  BUT there are still a load of good launchers which will be compatible with your phone and will provide the functionality that you're looking for.  Have a look at:


Go Launcher
ADW Launcher