What to put in bassinet insert for newborn to sleep in?

Hi. I have this with the bassinet insert. What do i need to put in it for the newborn to sleep in beside my bed? Like sheets or what or anything else before putting the baby in. And what type of sheets to buy? Like are there any specific sheets for this? Should i buy pack and play sheets but for the bassinet insert will the pack and play sheets fit in? Or what sheet to buy for bassinet insert?

Please suggest. First time mom here. Thank you