You can get direct admission in BITS only if you are a board topper of your state or zone. For the conventional procedure of admission you have to appear in BITSAT i.e. an entrance exam coducted by the BITS for their intake. The application forms are available usually from second week of january.  In April you get the admit card which has exam date, time and venue on it. The exam score is available just after the submission of the test. Then the candidates have to apply online with the test score and the 12th score mentioned in the application. As you have score 80% in PCM, you are quite eligible to apply for the BITS. The physical education marks doesn't matter much if you score good in the BITSAT. If haven't applied for the BITSAT already then you are too late for this year's intake. You can choose from some other good options or wait for the next year.

All the best!