You should first install Synergy on your main computer. Simply download it from Synergy's website, select the one appropriate for your operating system. Install it as normal. Check out Synergy's help page.

Before starting the server, configure the server to accept connections from a computer named "pi". Configure the hot-corners or hot-keys as you desire.

If you get a server/client verison mismatch, make sure you're running 1.4.15. If you're using Ubuntru, try this package, which is able to sucessfully install synergy 1.4.15 on ubuntu 14.04.2:
https://launchpad.net/~eugenesan/+archive/ubuntu/ppa/+build/5381426

The command I used to install the package was:
sudo dpkg -i synergy_1.4.15-0-eugenesan-lucid1_i386.deb

At first attempt, it didn`t work because of some dependency problems. To solve that, I did two things:
1 - Ran this commands:
sudo apt-get install -f
sudo dpkg --configure -a
sudo apt-get clean
sudo apt-get update
sudo apt-get upgrade

2 - Installed libcryto++8 manually, downloading it from http://packages.ubuntu.com/lucid/i386/libcrypto++8/download

(thx andre!)