Angela Wrightson, 39, was also battered with a stick with screws sticking out of it by the then 13 and 14-year-olds, it was said.
Ms Wrightson's body was found at her home in Hartlepool in December after a "sustained and brutal assault", Teesside Crown Court heard. Medical evidence showed she had more than 100 injuries.
The girls deny murder.
Jurors heard an array of items were used in the attack.
Nicholas Campbell QC, prosecuting, said: "A number of implements were used as weapons. They included a wooden stick with screws standing proud of the surface, a TV set, a printer from a home computer, a coffee table and a shovel.
"Smaller items such as a kettle and a metal pan were used together with a glass vase and other ornaments.
"There were well over 100 injuries. The evidence at the scene of the crime showed she had been struck in 12 separate locations within that room."
The court was told her blood-stained body was found by her landlord at her home in Stephen Street. She died as a result of blood loss.
Mr Campbell said: "It became clear that Angela Wrightson had been the victim of a sustained and brutal assault."
The younger girl took selfies at the scene and published one on Snapchat, the court was told.
Later she contacted a friend using Facebook, and that witness went on to tell police during the call she heard the defendant shout: "Go on, smash her head in, bray her, kill her."
Both girls were jointly responsible for the fatal attack, the prosecutor told the jury.
The court heard at the time of the attack the pair, who cannot be named, were in the care of the local authority.
Now aged 14 and 15, the defendants had formed an "intense relationship".
Ms Wrightson was an alcoholic and in drink could be a nuisance, the jury heard.
She allowed young people to drink in her house and would buy cigarettes and alcohol for them from a local shop.
The trial continues.
Two teenage girls bludgeoned a woman to death with a shovel, TV set and a coffee table, a court heard.