confusion

Hello to everyone ! Here is my 1st topic OK i have a problem. I've received today (yaha !) my new computer (see the pics below). For this, i've used the case Thermaltake The Tower 900 (the most beautiful imo ). The problem is .... (#### i know that i'm gonna look stupid ...) I don't understand how to access to my motherboard and my graphic cards (SLI 1080). I know that behind the case, at the top, i have 2 buttons to push, to open the lateral panels. And from what i know, the access for the MB & CG's are on the top panel. but i just don t understand how to remove this top panel ... Thank you in advance for your help ! Without you i can 't start with my new baby !