What routes needs to be added

My host machine has IP 192.168.3.x and my guest virtual machine has 90.34.4.x I caot ping from guest to host and vice versa. My host machine can reach other networks. What route needs to be added on to guest so i can ping host and all other subnets which my host can ping. My guest vm has redhat linux. can you help me with the command.

Matt