Object oriented design class vs object

I am trying to make object oriented design of this assignment posted below. I couldn't design this, so I let it be. Now I tried to implement it for fun, and so far it looks like I need only

class LoadAdReport{
public function LoadCsvReport($report, $columnNames);
public function LoadXmlReport($report, $columnNames);
public function LoadJsonReport($report, $columnNames);
}

and database work in

LoadAdReportModel{
}

It parses all reports into array with same format. But now I went back and looked at the assignment and it looks to me like I should specify everything in code, so it assume how the report will look.

So something like this

interface LoadAdReport{
public method LoadAdReportData($data)
}

now I am not sure with this, as I read the assignment then I don't know what should advertisingSystem class do, maybe advertisingSystemReport class, as each adSystem has different structure of report, then maybe some format class which handles converting it into an array which will go into DB. class bing implements LoadAdReportData{ }

class AdwordsReport implements LoadAdReportData{
} 

Okay so, every ad_system has differe

You are building application that will load data from several different advertising systems and then store the data into database, so it will be possible to analyze them.

You need to take in mind that every advertising system has different structure of report: Different named columns, different order of columns, different date formats Also data from ad systems are in different data formats(JSON,CSV,XML),

Reports from each system contains different amount of columns, our application is interested only in some of them: date, ad_campaing, ad_group, keyword, impressions, price (in every system they have different name)

Logic of advertising accounts is that one ad campaing contains multiple ad groups and one ad group contains multiple keywords.