Error: openssl can not recognize as internal and external command

I installed openssl following this tutorial Tutorial: Particle-cli on Windows [07 Jun 2015] but still it can not recognize.

Have you restarted your computer after installation?

OpenSSL needs to be part of your PATH to be found by Windows.
When you open a command line (cmd) and execute path you should see the derictory where you put OpenSSL somewhere in that.