Decrypting a file with a .sec secret key ring

Hello, I'm new to the forums and PGP command line. So I would need some friendly advice here

I'm trying to decrypt a file with a .sec secret key ring file given from my friends.

I tried doing all sorts of commands but I still couldn't decrypt it.

Here is a sample of the file (in rar) : https://mega.co.nz/#!GFxQHSpT!ogmm4ZvJybii1_YSjVhIXCc43j2tDyJuZQChds0OhLk

Hope I would get some help, much appreciated.