How do I start studying for 1st semester PTU as I joined late?

Although you have joined late studying for 1st semester at PTU, still you have very good chances to score well in your exams. If you work hard enough and be sincere with your studies it is definitely possible.

• You should first make a time table and start preparing according to that. 
• If some subjects seem to be difficult then give some extra time to those subjects and try understanding the concepts properly. 
• If you are having any doubts regarding a chapter then discuss it with your teachers. 
• Don't put much pressure on yourself in 1st semester itself. 
• Keep working hard and try to give your best. 
• Interact with peers, teachers and seniors, they can guide you as well. 

Thus joining late would not affect your study patterns and exams, as you will get enough time to prepare for it.