Slow down, take a deep breath it's not hard! It should not be hard particularly if you are on a city water supply. If the system is old you'll want to check that there are appropriate backflow preventors on the system and that they are installed correctly and that they work
. Once you have that you install an inline pressure regulator to get the pressure down and simple inline filter on the line at the manifold where your valves are. This helps keep the drip lines from clogging. If you have pop up sprinkler heads you can easily retrofit them with drip. If you have the old style fixed spray heads you can still retrofit them to drip but it may be more work if you want to hide the drip lines. The whole conversion is very easy because your main lines have already been trenched. Trust me I've trenched my own lines and this was hard tiring work even with a trenching machine.
Thanks for the info. TBH, it seems like describing the process at a high-level is very easy, but each of those steps you listed probably has some education that is needed to set them up properly, know what to look for, research into brands, etc.
Some good info here: http://www.urbanfarmerstore.com/converting-sprinkler-to-drip...