How to change flat boot to platform boot

Hello everyone, I am wanting to try to change a pair of flat boots (like doc martins) to a platform boot (New Rocks) and have never done anything like this before if anyone has any advice or video tutorials ( I learn Best Buy watching someone else do first) I would be so grateful !!! Or better yet if anyone knows where to find a pair of black boots that look like New Rock boots for size 8.5cm Ringdoll foot that would really help, thanks everyone p