Fatima,
The Google Picasa help file says that printing photos at home uses your printer's settings. This assumes, from what can tell, that the printer would be installed on your home network and that you are connecting to the printer through software on your computer / device.
Google Picasa - Print photos at home
Google Picasa - search "trouble printing Picasa photos"
In other words, "it" has to be set up -- the definition of "it" depends on what you are doing.
Example:
- Printing while logged into a Windows machine requires printer software to control the printer on the computer.
- Printing from a phone requires some sort of mobile printing software be installed on the device so it can reach your printer.
See this document - it includes information about Google Cloud printing:
How to Print with an iPad, iPhone, or iPod touch
Click the KudosStar!
It is a nice way to say “Thank You” for the help.
Although I strive to reflect HP's best practices, I do not work for HP.