MacBook update problem?

Hi i just bought a used MacBook from a friend i have been having a problem when trying to use the software update. it says in network diagnostics "network diagnostics was able to connect to the internet but not to the server "(not showing the server for privacy reasons)" This could be caused by problems with the server, or an internet problem between this computer and the server."

I pretty sure it has somthing to do with my friends job he works at thats why i did not supply the server name i just want to know how to change the setting to allow me to update my software from my home wifi thanks

I recently downloaded apple quick time and itunes but later uninstalled them…However in my add or remove program list there is an item that says "Apple software update" when i click on remove I get an error that states "there is a problem with this windows installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor.

If I click on change and then repair I get "the feature you are trying to use is on a network resource that is unavailable. click ok to try again or enter an alternate path to a folder containing the installation package ‘applesoftwareupdate.msi’ in the box below"

Anyone know how to resolve this so i can remove this from my computer?