Agree with the above. There are lots of smaller scenarios, especially in the downloadable user created scenarios, and people create new ones all the time. Play LOTS of the smaller ones so you can focus on a manageable amount of assets and get used to the mechanics.
If you've played Harpoon, I think you'll actually feel at home. CMANO is a bit of Harpoon on steroids and updated. Many of the concepts and mechanics will seem pretty familiar. That being said, the complexity level and detail is a big step above Harpoon (IMO).
There is a ton of information on line to help. Baloogan's site, many many youtube videos that will demonstrate concepts and after action reports. There is lots of help. And also, this forum, which has some of the most involved, knowledgable and helpful people of any that I've been on. You'll always get good answers, and in many cases I find, get an education about real life capabilities.
Dive in. The water is fine! :-)
"When the Boogeyman goes to sleep he checks his closet for paratroopers"