It's probably best to start customising the stock launcher.
Long press on your screen and you get options to move the icons about. Menu button at the bottom lets you change wallpaper. You can add and remove screens.
To change the icons in the Dock (fixed ones at the bottom) you need to be in the App Draw (icon at the right of the dock by default). You can then use the menu button to drag stuff into the dock.
Once familiar you will then want to look at an alternative launcher: Apex, Go Launcher, AWD etc.
I use Go purely because the folders you can put on home screens are nicer than any of the others.