Get bit value from a char array.

Hi guys,
I’m trying to activate the lock bit of an Ultra Light nfc card. It has the following structure.
there are 16 pages. 1 page contains 4 bytes. Lock bytes are available in the 2nd page 3rd byte and 4th byte.if i want to lock page 7, i have to change the bit value of 2nd page 3rd byte 7th bit.
I can go to the 2nd page 3rd byte but HOW CAN I GO TO THE 7th BIT.

Please help me.
Thanks in advance.