I am a ASTU student. First of all ASTU doesn't teach modelling, but if you were trying to mean something like architecture, you have to first take the exam to join ASTU. After you join, you will first learn pre-engineering for a year then you have to choose the school you will learn in. If you are planning on learning architecture you will put School of Civil Engineering and Architecture. You will then learn common courses for the first semester and you will choose your field, which would mean you will put architecture as your first choice from the departments, but as far as I know it's not as easy as other departments in order to join, I am not saying it's impossible but all you need to do is work hard. I wish you all the best.