Pop-Up Windows

I've been trying to figure out how to put pop-up windows on a website so that when you click a link a new window will come up. So far I still haven't been able to figure out how to set the size of the window. This is as much of the code that I have:

<a target="Here" href="H:\Widget Website\pop up.htm">
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<iframe name="I1" marginwidth="1" height="0" scrolling="no" align="center" border="0" frameborder="0" src="H:\Widget Website\pop up.htm" width="0">

You should only need to change the things in red.