In many cases, ZIP files will contain the same folder structure hierarchy that is found in your runtime folder under Poser.  The Runtime folder is the folder that Poser accesses to load the content properly into the app so you may see them in the different library subdivisions.  For example, your hierarchy will look like this:

*Runtime>Libraries>Character>(Content Author or Content Name)

*There maybe underlying folders under the Content folder but that is preference of the vendor.  The important and essencial subdivisions of the runtime folder which appear in Poser are:

Character
Hand
Face
Camera
Hair
Props
Light
Pose

If the ZIPPed content follows this convension exactly, then you can unZIP it directly into your Poser folder and everything will appear properly in your program.  As you accumulate content, you would want to consider creating external runtimes to ease the Poser startup process and organize what you have and want to use.  This may be something your would like to start from the very beginning before content growth overwhelms you.  And, by all means, play with the program and have fun.  Frustration is part of the learning curve and so is experimentation.