This question already has an answer here:
I am new to Ubuntu and I have recently burned an Ubuntu .iso file on to a DVD and booted in to Ubuntu.
My disk is 80GiB and it is already partitioned in 2 parts. C: where the Windows is installed, this is 65GiB, and the second partition is 15GiB.
I want to install Ubuntu alongside Windows 7 and preferably in the second partition (15gb). Which option should I choose? "Install alongside Windows." or The Manual install or something else?