Q: Best way to transfer my aperture images to my WD my book duo external drive? and should I change from raid 0 to 1?

I have IOS 10.7.5.  My internal drive is almost full out of 999 GB I have 39 GB free most are photos.  The RAM is 16 GB Processor is 2.7GHz Intel core i5. Best most efficient and quickest way to do it. As you can see I am panicking. Thank you