enabling remote access SSH -

Hi, I'm trying to configurate my LAN to allow a remote consultant log-in via SSH to one of my computers. I have a TP-link TL-WR740N router whit 3 computer's on my LAN. 1 - Linux server 2 - Linux server 3 - Laptop whit windows on it. Even if remote access is not possible on the Linux server I want to allow port fwrd access. I have putty installed on my windows that can connect to my Linux server. I have my router configuration page already open in a browser and I have teamviewer installed. I need someone that can configurate 1 of my Linux server to allow remote connection via SSH (port fwrd in my router). Thank you