Instructions for "adventure"

Is there somewhere, instructions on how to play in an adventure besides the tutorial which doesnt cover much ?

Check out the forums here there is a post called adventure guides- it is A list of walkthroughs for most adventures.

There is a very simple adventure you can buy with a fish in the store. It's also sent to you as you level up.

Keep in mind the "how to" adventure in the guide section is outdated slightly. It's still great information but a few things have been tweeked during patches.