Transportation in HK.

Your hostel is near Mong Kok Station of Tsuen Wan Line, so you can take this line to reach Central, make your way to the J2 exit and walk up to the ground level. Turn right, through Chater Garden, cross Queen's Road Central, and make your way up Garden Road. Then you will find the ticket office to Peak Tram.
To Ocean Park, you can directly take Bus No. 629 starting from Exchange Square at Central to reach.