Main interface : activity panel (upper-left), reminder (upper-right), stats (down). You can also click on the TV for fun and use the phone (that squarish thing left of the books...) to dial numbers yourself.
Activity panel (from left to right, going down) : Litterature, Science, Art, Sports, Club... Chat, Fashion, Sleep... Phone, Date, Magazine... Options, Calendar, Load/Save.
The first options are studies related. The club one lets you choose a club first, and then you choose it to go to the club. Chatting is good for stress and common knowledge. Sleep is mandatory when your stress goes up or your health is down.
The phone lets you either call a girl on a date, or ask one of your male friends for intelligence on the girls (phone numbers, tastes, clubs and what they think of you).
The magazine lets you know of incoming events, date spots and other such things.
The calendar lets you review every incoming date, school test, vacation and special days.
The activity panel can be arranged in two other fashions :

When doing an activity, it's either for the whole week, or during the weekend (which is reduced to Sunday, Saturday being included in the week). You can see a little 3D animation (2D in TM1) of the activity and wether you succeed or fail, day by day. Stats go up and down depending on this. Each activity has an effect on multiple stats, good and bad.
Calling a girl to go on a date. I need to phone my male friend first to know their numbers ^.^. If the girl was home and available, I can...
... set a date and...
... pick a location.
Depending on all this, she can accept or refuse (club activities, something planned with a friend on that day... or simply because she doesn't like me ;o;).

DEITO suruze~! The date takes place in regular VN fashion with the girl saying something. You then get to choose between three possible answers. There's a good, a neutral and a bad answer. I'm pretty sure that the place you take the girl to has some coefficient which means if you answer good on a good place, it's *really* good. But if you answer bad on a bad place, it's *really* bad ^^;... She might also not take it well if you say you're bored in one of her favourite places.
Double-date! Along with a male friend of course. Those are special events occuring throughout the 3 years of the game.
There are also exams taking place every few months... and this is the result panel. Some girls don't care how good you are while others will only date the best of the best ^^;.
Well I guess that's it for now

. Should be enough to get ideas. I think I could get a video if you need to see all this running together.