Right click on an icon in the Dock if you have a two button mouse, or with a one button mouse on a laptop hold down the Control key and click. You’ll see a little pop up menu with the option to “Remove from Dock,” among others. (You can also click and hold the mouse to see the same menu.)
Select “Remove from Dock” and the icon will be gone, but not the program. You’ll still be able to use the program from double-clicking on it in the Finder.
If you find you want to put the program back in the dock, or put another program in the dock, find the program in Applications and drag the icon to where you want it in the dock.
You can rearrange icons on the Dock by clicking and holding down and dragging them around.
With that right click menu, you can force quit a program that quit responding, and also set a program to start when you login.
There is also a Preference Pane that deals with the Dock. Go to your System Preferences and select “Dock” in the top row. In that window you have the options for Dock size, location and magnification, which is the way the icons get bigger when you hover over them.