You need to forward ports when behind a NAT router.
If you explain what software you are trying to use to do remote access, it will simplify things in answering your question.
But here is a description of the general problem:
. You need to obtain the Public IP of the WAN interface that hosts the computer you want to connect to. The link I gave you above will reveal this for your Home machine; using DDNS as a long-term solution is advised.
. If your Home machine is not behind a router, then this is all the information you need from that device EXCEPT that your firewall software (if used) needs to allow traffic from the remote computer to pass-through. Again, you need to specify the program you want to use.
. On your Office computer behind a NAT router, you need to create port forwarding entries. This is very much software specific. But the general notion is simple: create in the router setup pages a port forwarding entry so that when traffic appears on a specific port it is directed to your LAN IP (the 192.168.x.x) stuff.
. If you are using DHCP on the Office LAN, you might ask the IT guys to create both the port forwarding entries and to give you a Static IP address. This can simnplify things a great deal.
So, what software are you intending to use for this remote connection?