The top 2 sata ports is were you would put your hard drive and DVD. Note the Gigabyte sata is a different sata controller good for esata that is for external drive.
This is on page 7 of your manual. You could plug them in another sata slot as long it is not the Gigabyte sata control but most use satll0 for the hard drive. Are you going to install more than one hard drive? Sata has no master ,slave like ide controler setup. Are you going to install a external dive?
Satall0 Hard drive