Dear Dhananjoy.
"Principa"l Word it self covers entire functions,process,activities related to school,administration,education,employee management,development of school as well as development of over all areas of students personality by which the school may produce a quality product.
As you have not mentioned about your prior experience, and number of employees total having in school, number of students,atmosphere of school,which type of support and back up is given by top management and what are the expectations of top management from you in terms of increasing number of students,time frame and power to work on quality education .
If you have been on same post earlier then it is good for you but if this is new trade for you then try to contact and connect some same profile persons known to you by any mean and start pointing your target for proper development of school by analysis of present system and atmosphere.
try to connect with experience staff members and collect important information, get feed back of faculties, teachers and related staff, have a look of parents feed back given for school etc.
These things will link you slowly but strongly to system, and as a principal you have big responsibility of quality education,team building ,co ordination with staff,faith of parents and so on.
Soon you will manage the things..
Best Wishes.
Manish Srivastava