gleplae; Hi ! Welcome to the forum.
My first guess is: primary partitions on the hard drive. One may only have 4 primary partitions per disk, and often windows takes up all four of the partitions. If this is the case there are means to make a partition available for ubuntu to be installed on.
To see the partitioning:
Boot up the livecd in "try ubuntu" mode; ctl+alt+t key combo -> command line interface.
Enter these terminal commands:
Be aware that the use of sudo elevates one to administrative authority.
sudo fdisk -lu
sudo parted -l
just try'n to help <== BDQ