This modpack requires 3-4 GB of RAM & Java 8 64 bit. http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
Type in the modpack name (Wizardz Conquest (Beta)) or paste the following url into the search box.
Finally, click Install at the bottom right of the launcher after you select Wizardz Conquest (Beta) from the list on the left. The launcher will handle everything else!