2TB External HDD Drive Question (Windows 10 Backing Up)

Hi all its Been a while having alot of stress
And personal and family troubles 2017 has been a rough
Ywar for me,and the rest of my family, I don't like taking
Anti depressants and I'm a really short guy and don't want to
Be 187LBS and standing 5'4" tall had about 12 ex-girlfriend
Who were taller than I am from 5'9" to 6.0" and taller with Heels on
But you guys are smart, I'm sure you are.getting what I'm saying.

I have everything for my PC Minus the usb ports dust covers and the ones.that.cover the tip
From the evil dust bunnies. And I'm going to be temporarly recycle
My current system graphic card irs a AMD RX 390 8GB card to use in the
new rig. Till I get a NV 1070 CARD or try the new AMD
Vega GPU that has been released. Back to the topic
I am using a WD elements 2TB external drive and has about
1.7TB left. I was hoping I don't have to reformat the HDD
Because I only have one drive that has the most space I'm asking
If I can keep what's already on the drive as and create a HDD
BACKUP Img bring it back to all programs mainly have iIn order
So all I can do install digital games and what not.