To start off the UI introduction, I'll begin with the main info page. It's the very first thing which will pop up after you logged into the game.
So the top banner will scroll through the events that are currently ongoing. For example here, there's some sort of registration event for the upcoming Maoyuu collaboration.
At the bottom are links to new information, which you can tap onto for further detail.
Tapping onto the banner will bring you to the detailed event information page, shown below.
The top left button will bring you back to the main section of the Events page.
That's pretty much it for the main info page. Pressing the cross button on the top right corner will exit the page and bring you to the world map.