Re: Ubuntu install - partition query
You should probably first do the following: open a terminal and enter "sudo fdisk -lu" (lowercase L, not a one). This will list out the partitions on your drive along with their filesystem types and sizes.
Presuming you want to overwrite Win7, if it came preinstalled, there would be two partitions -- a boot partition and a Win7 OS partition. If you installed it yourself, there is likely to be only one partition.
But, either way, Ubuntu will not install to a Windows filesystem partition -- which may be why your not seeing the option you want.
If you really want to install over Win7, then boot from an Ubuntu LiveCD or LiveUSB, choose Try Ubuntu, when the desktop comes up, use the Dash to launch the Gnome Partition Editor (GParted) and use that to remove the Win7 partition.
You can then install Ubuntu into the free space using the "something else" option.
Ubuntu 16.04 Mate, Mint 17.3; MS Win 8.1, MS Win10 Pro.
Will not respond to PM requests for support -- use the forums.