I am starting to play this game and have to admit the tutorial is not that helpful.
The tutorial is sadly very brief, with the instructions ending once you are about to start building military buildings. An unofficial patch being developed aims to fix e.g. this problem in the tutorial (making the instructions appear until you got the necessary stuff for producing soldiers).
On the tutorial map there are two set of enemies (blue and yellow: with the yellow one is pretty strong), blue on the top left and yellow on the top right.
The blue team is actually on the bottom left. Yeah I realize it was a typo. Whilst the yellow team does have a pretty strong army at the start of the map they are unable to produce more soldiers so the blue team will probably be more of a problem to defeat in the end.
My advice is to use this tutorial map to get yourself familiar with the battle command and tricks because the tutorial map allow you to have quite a lot of different types of building unlike the first three real campaign which you are quite limited. The type of troops you can have are limited by the resources you have in your town (thus limited by the building you can have).
Having less buildings to worry about in the first missions of the campaign might be pleasing for a beginner, though the enemy never attacks in the tutorial which does make it more relaxed.
The trick used by pretty much everyone when playing this game against the computer whilst attacking is to take a single bowman and lure an enemy troop to follow it by having the bowman attack that troop. This allows you to lure the enemy soldiers into a position with less enemy troops and with some well placed bowmen (and towers in later missions) and with some axe fighters to protect them, you should be able to win over a considerably bigger force. If you set up the ambush close enough to the enemy main base, they should be sending their whole army to your ambush after you've killed off the troop that initially started following you.
I do have to very often refer to the manual for which people are for the specific building....
You can find out which occupant a building needs just by clicking the building once it's been built and then hovering over the citizen icon next to the building condition/hitpoints.