Changing Info.plist values via terminal

I am making my own application and I would like to change some values in my Info.plist file using terminal.

I have tried doing defaults write Info.plist CFBundleExecutable -string <Executable> and defaults write Info.plist CFBundleExecutable <Executable> however it never seems to work. I don't get any output so I don't even know what it is i'm doing wrong.

Thanks for the help