In short, any port will work for either device.
Unless you have some kind of super fancy hard drive or a solid state drive, you won't really notice the difference. I'd say put them in the SATA3 ports anyway though. Mechanical drives can never hope to bring out SATA3's potential because they have moving parts. Even more so with optical drives that are even slower.
If you you have multiple hard drives, bios will automatically boot of the hard drive in the lowest numbered port unless you tell it otherwise, so I tend to put the drive with my OS in the first port.
I'd say just plug them in your two SATA3 ports. If you get another hard drive in the future, bump the optical down to one of the SATA2 ports.