He contracted with someone to commit a murder. That's doing something. This makes him part of a conspiracy to commit murder.
The article doesn't specify what Ling was sentenced for. I assume it's for this conspiracy, but it may have been for other crimes the police learned about after Ling admitted to being a career criminal (unless this was their first contract). If you tell the police you're a murderer, they'll likely try to get you for it.
It's not clear that he committed to a contract or was offered a contract. Generally, the elements of a contract are: offer, acceptance, consideration, mutuality of obligation, competency and capacity. We don't know.
Conspiracy is easier: two or more people agree to commit an illegal act and take some step toward its completion. But I don't think if Joe asks me to kill Bob for $100 and I say sure but then go to the police that I've actually agreed to kill Bob.
The article is very light on details and certainly doesn't mention what the charges were for Ling. Also, this is China with a different legal system.
Given that the article is light on details, why are you assuming that Ling was just an informer and did nothing wrong? The details we do have indicate that Ling did enough wrong to warrant a sentence of 2 years and 7 months.
It might be conspiracy to commit murder, or it might be fraud, if he was intending to take the money but not kill anyone.
What do the police do when they catch someone who was selling fake illegal drugs? It can't be a drugs offence, can it? But I'd hope they prosecute them for something.
