So I have already made a partition of 100 GB in windows but when I loaded ubuntu 13.10 from a usb stick and tried installing it ubuntu didn't give me the option of installing along side windows. When I clicked something else and then clicked on 100 GB free disk space it still wouldn't let me. This is the first time for me to install a new OS so simple anwers would be the best.
100 GB partition created on Windows should not be an ext4 partition,so you can't install Ubuntu on it.
Try to format the 100 GB partition into ext4 filesystem.To do this,
Note:Make sure that the 100 GB partition is unmounted.