Help regarding custom payment provider

[TALHA0713]

HI everyone,
I want to create a payment provider and i have integrate medusa v1 docs can i shift to V2 instance withou facing any issue.
Also i want to create add online payment method which works in Pakistan so for this i want to use the jazz cash or any other payment gateway but i dont know how i can do this
for that after reasearch i am found this
and am add in my code but I did not understand how i can add my payment gateway attach in my cart i need some suggestion and proper flow
Please give me some support
this code is write in backend admin code or store front code also ???
I want to ask some question also
[email protected] thats my email please contact me i want to ask some questions regarding this