Meaning of different command prompts

Unix/Linux: $: can be run as normal user
Unix/Linux: #: must be run as root (or with sudo)
Windows: >: Command Prompt or PowerShell
Windows: PS>: PowerShell only
Unix/Linux and Windows: $/>,#/>: Works in Windows and Unix/Linux.

From the directory you want to save your certificates to, such as /etc/ssl, do the following:

$ openssl req -new -newkey rsa:2048 -nodes -keyout for.example.key -out for.example.csr

CAREFULLY enter the information that it prompts you for.

Copy the CSR file (and not the private key file) over to the Certificate Authority, and copy the signed certificate to for.example.crt.