How to make shortcut depends on if you run picasa in wine or using picasa 3(beta) for linux. Generally there are two ways to create a shortcut. The traditional way would be to make a symlink from ~/Desktop to the launcher(icon on desktop). If you're using gnome-desktop, just rightclick on the desktop and select "new shortcut" and put the path to picasa there. If you want the shortcut in menu, you have to edit the menu-entries, usually rightclick on menubutton and 'edit'. The path to start will be the same.
For picasa in wine the shortcut should be something like; /opt/google/picasa/3.0/wine/drive_c/Program Files/Google/Picasa3
For the beta version native for linux, the shortcut should already the in [Applications --> Graphics --> Picasa]
AMD Quad-Core, 4GB RAM, ATI HD3650silent, 33TB harddrive Laptop:
Lenovo Thinkpad x201, Intel core2centrino P9600, 4GB RAM, 750gb