cleaning tank

Hi, I am beginner and never owned fish before, I have recently brought second hand tank where it came with all the equipment and ornaments for the tank, how would I clean and disinfect the tank and the accessory it came with that won't harm my fish? - Gravel Vacuum - Fake plants - Pebbles -...

Hey, Just setting up my 80L Aqua One 620. It's second hand so i was wondering if it could harbour disease? I'm putting in new gravel and water in. But using the ornaments and plants that came with it. I will be cycling the tank also for the next month or so, will this eliminate any possibility...