If someone is accused of having child pornography, the police will usually obtain a search and seizure warrant for their home and computer
. They'd raid the person's home and seize any evidence, and the computer as well (if it is electronic pornography that has been alleged). The problem is in getting the search and seizure warrant. A tip is not necessarily enough to obtain a warrant. It has to be proven reliable. Otherwise anyone could run around accusing people of things to get the cops to raid their house. Even if they got the warrant, they would not arrest or charge the person without actual evidence of wrongdoing. So unless this person is actually planting evidence, the worst your character will go through is having the police search his home (and not likely that).
If evidence is planted and it is enough to establish probable cause
, your character would be arrested and booked into jail. He will usually see a judge within 48 hours to have a bail set and then he will be arraigned (plead guilty or not guilty). A trial
date would be set. He would likely get a lawyer at his arraignment (or appointed a public defender if he can't afford one) because it is insane to face such charges without a lawyer.
If the person just makes a false tip, they will not likely be charged with anything because it is hard to prove that a false tip was made. They could be charged with making a false statement to a law enforcement officer, but the cops won't likely pursue it unless they can show the information was provided in bad faith. If they planted evidence, they can be charged with obstruction of justice