Reddit reviews The Bluffer's Guide to Football (Bluffer's Guides)

Some of the previous comments seem to jump ahead a bit, with books or sources aimed at people who already enjoy the sport. Based on your own admission of coming from little to no knowledge of rules etc a better approach in my opinion would be to pick up a book similar to this. Note that it was one of the first I found, so there may be better beginner books out there. I recall my dad having a beginners book on coaching when I was younger, will see if I can find it tomorrow. It covered several aspects such as practice routines appropriate for different ages, the rules of the game and how to help the youngsters to get better.

Depending on how expensive it is, getting level 1 coaching badges from the FA may also be a sound approach. Approaching the game as a coach is very different than as a fans. For the most part, yelling stuff from the sidelines during a match is rarely going to help unless it has been mentioned during practice. Remember that the coach is there to help the players get better. As an aside, I recommend trying to make it fun and put less importance on the result if possible. I've seen some ugly cases of parents screaming at kids similar to what fans do at the pub.

Will try and update with some links to coaching classes online or better book examples tomorrow :)