Question How can I use my current HDD in new mobo

Mar 26, 2019
So I just got the new components to upgrade my PC but I didn't got a new hard drive because I'm dumb and didn't thought about that (it's my first build/big upgrade, new mobo, processor and RAM). I was looking for a way to use my HDD and found that the best way to do so is to do a backup and then format it. But how can do it? Just right click and then format? What do I have to do next to use and install it for the next mobo? How do I install Windows and the drives I need for the components? I'm gonna keep looking, but I also wanted to ask, thank you in advance c:
If it's a better solution I could just take it to someone to do it for me but I wanted to know how to do it myself, like I said I'm new to this and didn't wanted to screw this up
Some additional info that I saw was important is that I'm changing processors from AMD A10 to Ryzen 5 and the mobo from NVIDIA to Asus
Feb 25, 2019
If you want to install windows on old drive you don't have to worry about it because when windows installation begins there will be a button that will allow you to compete format your HDD. At least i did like that when installing Windows 10. Good Luck! :)