Thsi is my first time changing the brakepads on my bike and I have no idea which ones are compatible with it nor do I know how to change it.
Please help
YouTube has plenty of videos to walk you thru changing brake pads, relatively easy task. Basically remove a cotter pin. I would check with a Rad dealer for finding the proper pads
I see you have Tektro HD 350 brakes. My Radrunner 1 has Tektro mechanical brakes. I checked the dimensions of my pads, looked for Tektro brake pads at Amazon, found that most matched my dimensions, and chose the pad material I wanted.
Here's a page that shows three pads that fit your brakes.
https://perfectbrakes.com/bicycle/tektro/hd-e350-e-bike/HYDRAULIC/4000367
As Carcosa said, youtube videos show the process.