We are going to create the / partition for the second partition, so choose the primary partition for the partition type. Key in what size you want to assign for the / partition. Remember the / partition is where we keep all the Ubuntu desktop system file. If you have a large hard disk, for example 160GB for Ubuntu desktop, then, the size between 20GB to 30GB assigned for the / partition is a reasonable size.

Choose Linux ext3 for the file system type and choose / as the mount point. Click OK to proceed.