I decided to change my bike's brake pads myself. My bike has the following brakes: Promax DSK-915. I contacted the online shop I ordered my new brake pads (and my bike last year), before purchasing, and they told me that these are suitable for my bike: Cox DBP-06.87-R Disc Brake Pads.
I got them today, but I have no idea how to put them on my bike, as the old ones I have are not rounded and have little hole that's used to put them in place.
Below you can see my old brakes. The "thing" (split pin/cotter pin) I circled in red goes in the little holes I marked with numbers.
I don't understand how I can install my new ones on my brakes:
Is that even possible? Or the online shop suggested I buy the wrong product? I am so confused.