Hamachi is basically a VPN. It just gives you access by IP to the machine. First of all, you have to make sure that it is running, as it may not add a line to come back from reboot.
Connection to Linux is different than Windows. You need to A have the port open, and B have the software running.
VNC is the most common for Linux GUI port 5900 or so depending on the setup
ssh is the most common for Linux command line port 22.
If you have port 22 open you should be able to ssh in at the least.
If you have another network with a computer connected to it you should try that first and make sure it works.
Most likely you need to install VNC on the linux server. What flavor of linux do you use?
- rs232c