Help with care of unidentified plant

Hi all!
I bought this beauty last weekend. On it it says green plant… Very useful. I think it's Pilosa Magic Mosaic aka Ctenanthe Lubbersania.
Since I got it the smallest leaf dried out and the bigger leaves have browning at the very tops.
It is still in it's original pot and soil, I keep it on a shelf near north facing window (since that is the only window I have), it is near the kitchen so I think hummidity isn't a problem? I did mist it twice.

Help. I don't want it to die but have no idea what to do.