-- Use collection runner and select external file csv , json 

        How does Postman know which column is used for which data in csv file ? 

        postman will look for variable with same name as column name 
        and set the value of the variable for that column name 

        for example : 
            if you have collection variable called zip 
            and you have column name for your csv file as zip 
            it will get the value from the zip column of csv file