Hi Jin - welcome to Crime Scene
You solve a case by competing in the different types of contests Crime Scene sets up by the end of each case. Those can be either a survey where you choose a killer and other case-specific information, or it can be a theory-summary, where you write in your own words what you think happened.
Prior to that however, theres the case of course. Crime Scene releases information on a case 3 times a week - on mondays, wednesdays and fridays. You can view a current case in the tab above titled "The Case". In there you find sub-categories on the different types of information you have access to. Some people prefer to solve a case alone, and other prefer to discuss the cases in here - it's entirely up to you

Paid members can Ask The Detective to gather more specific information about a subject, that you feel you need to dig a little deeper into. This feature can be priceless if you know the right questions to ask!
A typical case will run for about 8 weeks, and the Skull Found case has now almost been concluded.
Im not sure when exactly they'll start a new one, but you should stick around for that, so you can start on a fresh!!!
A case always remains unsolved before the whodunit-contest (obviously) - then afterwards we get to discover who the killer actually is. There'll be awesome prizes for the ones who get things right!
I hope this helped you out a bit and I look forward working with you on the cases to come.
- Azna