DOOR LOCK SYSTEM 8051

I have an issue regarding how to use 4x3 keypad to 7 segment,i dont know how to do the coding.I want to put 4 digit password to seven segment.Please help me on how to do it

You could start by looking at this tutorial on keypads.
http://www.8051projects.net/keypad-interfacing/

Download this project,
http://www.8051projects.net/download-d241-door-lock-system-using-seven-segment-display-assembly.html

Look for similar projects in our download section.

This should give you a good idea of what to do.
Ask again if you need more help.