How to connect to another PC in my office by just typing the IP in the browser?

Did you make sure the static ip addresses you used were in the same network segment? If your router uses 192.168.1.x and uses dhcp and has 50 ip addresses in it's pool like 192.168.1.100-192.168.1.149. Copy down the dhcp information the computer received and put everything the same except for the ip address. Use one that is not in the dhcp range, does not end with 255, 0, or 1 and is not being used by another device. If you are bored and using windows, you can google on how to modify the hosts file to point any domain name to the ip address of your choosing.