This page has a few links that demonstrate opening up new windows using JavaScript. The common building block is the "open" method, which runs using the current window. This is partly documented on page 288 of Joe Burns's JavaScript Goodies and also on pages 93-94.
window.open(url); Opens a new window looking at the supplied url, which should be a string.
window.open(url,name); Opens a new window, named with the supplied name, looking at the supplied url. You can use the name to control the window. Both arguments should be strings.
window.open(url,name,inits); Like the previous examples, but you can use the inits string to initialize certain things about the window. Here are some possibilities:
heightpixels
widthpixels
toolbaryes or no
menubaryes or no
resizableyes or no
locationyes or no
directoriesyes or no
statusyes or no

The open method returns a window that you can put into a variable and use methods on to write into. See the example on page 288.

Here are some examples: