How to make it look like an 18 year olds room

How to make it look like an 18 year olds room

so while i've been gone my father decided to do something nice. he added another room to our basement for me & wants me to move in. now the room is bigger than my last one but theres one problem... it's painted yellow. like not in your face blinding yellow but the kind of yellow you would paint in a babys room. its hideous. now i want to move in, but i'm not sure how to make it look like an 18 year olds room. he refuses to paint it. now i already have black furniture, so i'm hoping that will help, but man, i'm at loss of what to do. any ideas? here is a quick picture...
this is a picture of my old room @boarding school...i miss it.
Salut, salut!

Salut, salut!

nice surprise

nice surprise

Noob.

Noob.

the rest of the room

the rest of the room

Yay yay yay! Butterflies!

Yay yay yay! Butterflies!

plant ID pretty plz~?

plant ID pretty plz~?