Idol Screen

This is basically where you manage your unit formations and your idol development. Most will be explained in the tutorial you did at the start.
Idol status screen – Most of the time, you can press and hold down on an idol to bring up this screen.
Idol Units – Where you form your teams.
Lessons – Where you level up your idols. This is also where you use Trainer Tickets.
Awakening (aka Idolisation) – Where you can “evolve” your idol to a + rarity. Example is a Rare becoming a Rare+. This can only be done once an idol is max bonded by playing with them in a team in Lives. You will need the required items to awaken them, which can be acquired as rewards in Lives, or through the Room from the delivery shelves/pigeon holes.
Star Lesson – Where you raise the Star Rank of an idol. You will need the same idol to do so.
DismissTell an idol they’re a failure and boot them out of the office but not before robbing them of some cash. Where you dismiss an idol and gain some money back.
Idol List – List of idols in your possession.

idol

Idol status screen:

idolstatus
Raise levels with Lessons.
Raise Star Rank with Star Lessons.
Raise Bond by playing Lives.
Raise Skill level with Lessons.
Lock your favourite idols to stop accidentally feeding them to another idol.

Reaching max bond will allow you to awaken an idol to reach the “+” rarity. For example, a Rare will then be a Rare+, but no further than that. This will increase their max level, and unlock their alternative outfit.
Having a max bonded idol will also give bonus stats to her parameters.

Idol Units:

Set your teams! Your centre girl will have her centre skill active during Lives. If you put two of the same girl in the unit, one of the girls will be a randomly chosen girl for the Lives.
idolteam
Click on the favourites on the top right and you’ll be on the screen below. Here you can set you own favourite idols who will appear in the home screen and in the room. If you don’t set any, your “main” Unit will be used instead.
idolfavourites

Star Lesson:

What does Star Lessons do? They raise the Star Rank which increases your money received and increases your chances of rare items in Lives.
The catch? You need the same idol to “feed” into the other.
+ rarity (R and R+) are considered the same idol, but different rarity (SR and SSR) are not the same.
idolstar1

idolstar2

idolstar3