I need help with Picasa?

Picasa simply monitors and edits photos in folders on your PC. It does not contain your photos - if you uninstall Picasa your photos on your PC will still be there. Therefore, your photos are stored nice and privately on your PC (barring some bad security failure of your other software that connects your PC to the Internet and lets people browse the folders on your PC).

Picasa Web Albums (PWA) is an on-line photo sharing service that can be used with Picasa but that is entirely optional on your part. If you use it and if you upload copies of your pictures from your PC to the Internet, then you need to be careful about the privacy settings of the on-line folders in PWA that contain the photos.

By installing Picasa it won't remove your photos from your computer

I know this as I used to use it

Picasa is just to monitor , organize the pictures with in the system. So it won't reflect.