Before you start using all of your certus quartz crystals to make a bunch of machines it's a good idea to know how to grow crystals, growing crystals enables you to double the amount of crystals you have, this comes in handy if you are ever short.
Seeds are one of the most important parts of the "early game" of AE2. By combining Certus Quartz Dust or Nether Quartz Dust (produced in the Grindstone or similar process in another mod) with Sand, you can create items called Seeds.
The grindstone is the simplest grinding machine you can craft but it will also need a wooden crank to work. Placing the machine down and then shift-right clicking a wooden crank on the top will complete the machine. You can place any ore as well as certus quartz crystals and nether quartz within the machine. Holding the right mouse button on the crank will move it and after 4 rotations the machine will convert ore and crystals into dust, ores will be converted to 2 dust giving your early game ore doubling.
This dust can then be combined with sand to create seeds. Initially throwing these seeds into water will take a very long time to grow but this takes around 7 Minecraft days but thankfully these seeds will not despawn and this process can be sped up with Crystal Growth Accelerators.
For now throwing these into a pool of water will do. Keep an eye on these by picking them up again and checking their growth percentage while hovering over them with your mouse.