I installed and extracted the zip file that I downloaded from the Resources section. What should I do now i.e. where should I put the folder?

If you scroll down a little bit on the page where you downloaded it ( https://github.com/RedHaze/speedrun-demo-record-unified ), there is a guide on how to install it.

so the file i needed (speedrun_demorecord-2007.dll) was not there in the file what do i do

To quote from the install instructions, "2. Download the correct DLL from the releases page", which is here https://github.com/RedHaze/speedrun-demo-record-unified/releases