Well, it's not at all like age of empires online, so don't worry.
But yeah, you can just log in and play from where you left off.
In the game, you play as your city (either human, elf, or orc). You develop it and expand it, raise armies, you get the idea. There are lots of quests, especcially in the beginning; there's also lots of PvP. You have also have a hero (though hero customization isn't in yet).
It really is a good game, and new stuff is being added all the time now. So it's only going to get better.