Assuming that it's Common Anode, and I want to display a 4-bit no.(with switches) on two 7-segment displays , how?The first thing will be to check the datasheet for the pinout and whether it's common-anode or common-cathode.
Then you need to know how much the max. current for each LED, and you can go from there to determine if or what size of external resistor you will need for each LED.