How can i get the latest version of safari for my macbook pc? this time my pc version is 10.5.8.

Check in Software Update under the Apple menu that you have the latest Safari for your system. It won't be anything near the current version of Safari as your system won't handle that: you would have to upgrade your Mac to El Capitan to get it, and it's doubtful that your Mac can do that. The requirements for Mountain Lion and El Capitan are:

• 2GB of memory
• 8GB of available space

and the supported models are:

• iMac (Mid 2007 or newer)
• MacBook (Late 2008 Aluminum, or Early 2009 or newer)
• MacBook Pro (Mid/Late 2007 or newer)
• Xserve (Early 2009)
• MacBook Air (Late 2008 or newer)
• Mac mini (Early 2009 or newer)
• Mac Pro (Early 2008 or newer)

In order to upgrade to El Capitan you would have to first upgrade to Snow Leopard to get access to the Mac App Store:

http://www.apple.com/us/search/osx-10.6?src=globalnav

This may now be available only in the USA.