when posting for help like you are, it's helpful to include your model and year. Anyhow, I'll assume you have a 986 (post '98 to include side airbags). As such, take a look at this file. Yes it's about upgrading the sound system, but it includes instructions on how to safely remove the door skin. From there, it's a matter of peeling back the dust/foam liner.
Upgrade Boxster's Sound System by Andy_M
Good luck and search the archives on window drop, window regulator, etc. for more helpful tips on your problem.
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