Drag hosts from 'Windows\System32\drivers\etc' to your Desktop (No need for any other Temp folder) -> Edit the file and save it -> Drag hosts from the Desktop to your 'Windows\System32\drivers\etc' folder. Answer 'Yes' to any requesters popping up asking for permission.
If saving the hosts fails in Notepad, Right-click hosts on your Desktop, choose 'Properties' from the context menu. In the 'General' tab of the requester that opens, locate 'Attributes:', uncheck 'Read-only' and left-click on 'OK'. Now try and save the file again...
If you really would like to use your temp-folder instead, hold down [WinKey] and tap [R] - In the 'Run' dialogue, type %TEMP% and hit [Enter]. That brings up the correct temp folder for your user... It usually looks messy though and so the Desktop is more often than not a better place to work.