You don’t, and good thing too.
See another post around here about disabling the right click context menu and why attempting to interfere with someone’s use of their own computer is a bad thing. You don’t gain anything by it and will only end up a) looking clueless, and b) having a site with no readers.
If your web site design relies on things you can’t be sure of (software used to read it, window sizes, etc), you should probably re-think your design.
If you want useful replies, ask smart questions.