Armand
If you're a legal resident of Pakistan, you can either use an international driver's license if you have one or apply for a Pakistani driving license at any of the driving license centers. They will issue you a learner's license first and then after a month or two (don't remember right now) you have to appear for a written and practical assessment. Upon successful completion you will be awarded the license. You can get more details about getting a license in Islamabad here:
If you can let me know where are you located in Pakistan, I will be able to provide you more specific information.
Regards
TA