Shade,
Suppose you have uploaded this file "phpwcms_dev_1.2.6_14.12.2005.zip"
into this location on your account:
/home/shade/public_html/website/
then all you'll need to unzip it in this folder, will be to run these three commands (see in bold):
cd /home/shade/public_html/website/
you are now located in the good folder, then...
now run this command to check it's content listing:
ls -las
unzip phpwcms_dev_1.2.6_14.12.2005.zip
That's all there is to it
Cheers,