First of all you will need to download the Technic Launcher: http://www.technicpack.net/download
Then, once you have it downloaded and launched, search for "The 1.7.10 Pack" inside the launcher itself, thats the modpack we use for our server. You also have to make sure you have 64bit JAVA installed. Then its also smart to go into the launchers options and check that you have at least 4GB ram dedicated to the launcher, since the modpack is quite heavy.
Once all that's fixed just launch the modpack and add the IP: mod-mc.xtremeidiots.com:25565 and connect to the server
If you have any more questions @@DeathWaveUK, or if you get any issues, the easiest way to reach the mc admins is through discord. I'm always available there.