[header] How to host an 11 year old's birthday sleepover [title] Buy cheap pillows and blankets. [step] Line the floor of the chosen room with them, to make the room cozy, comfortable and good for lounging in. [title] Set up a bed for your child's friend/friends. 
[step] Cosy it with more pillows, cushions, sheets, blankets and possibly a duvet. If your child has a double bed, or a bunk bed, this will not be necessary.