How do I format the hard drive on my machine before installing?
When you get to the Installation Type screen, choose Erase and install Ubuntu. And if you're comfortable, you can go into Something else, and you can manage partitions the way you want.
Click on delete to delete the existing partition first, and then click on New partition table.
After that highlight the created partition and click on add. Create a partition with the shown mount point
but leave some space for a swap area