Press and hold the icon, then drag it to where you want it when the screen allows you to do so. By dragging the icon to the edge of the screen, it will hop over to the next screen.
You didn't say which Samsung "S" you have, but the newest S5 has folders and you can group icons to your liking, so you can fit a lot more "stuff" on the homescreen.
How to move icons, make folders, and adjust Home screen widgets on the Samsung Galaxy S5 | Android C...
