Hi Neti.
In the first instance, forget about Picasa.
Connect the phone (and accept whatever option is necessary to get it to talk to your computer; on mine it's 'mass storage').
Press the Windows key and E together, to open Windows Explorer and access 'My Computer'.
Look for the relevant drive letter and double-click on it. (If you're not sure which drive to use, just double-click on each of them in turn until you find the right one). Hopefully you'll then find the folder you're looking for and can double-click on it to access your images. (If Picasa is your default image viewer, double-click on an image to open it; otherwise right-click and use 'Open with').
If your computer still refuses to recognise the phone, try
(a) restarting your computer, disconnecting the USB cable, restarting your computer and reconnecting the cable ;
(b) another USB socket ;
(c) posting here again.
Chris