Complex sentence: The premise of the show is to take other people's rubbish which the presenter rescues from council refuse collection sites and with the help of a designer turns these items into desirable items which are then sold.
Split into simpler sentences: The premise of the show is to take items that other people have disposed of and which the presenter rescues from council refuse collection sites. With the help of a designer they are turned into desirable items, which are then sold.