There's not really enough story to warrant a walkthrough, but is there anything specific you need to know?
If not, the general way the game goes is: Drink with the grown-ups, exploit the kids young adults - if they get angry give them a gift every day until they aren't angry anymore, or wait it out. Work for money and if you play with ctrl as the most used key and nothing seems to happen, then you need to use the "talk" option.
You can make some potions in Snape's office, buy things in the Weasley shop (like the The Quibbler for when Luna shows up or the rulebook for quidditch) and then there is a dress shop for fun and to buy the dress that triggers the end game (which only ends the game if you want it to) ... oh and the "end event" is determined by how many public tasks you make Hermione do.