Time to get your hands dirty...

Practice Script - MyExerciseScript_GettingOhlcPrices_Qn.mq5

Answers Script - MyExerciseScript_GettingOhlcPrices_Ans.mq5

You can get these scripts from https://www.dropbox.com/sh/evwg2zasl8h7bzc/AACP9WG2aVvzVf-5TIMhLhyfa?dl=0 if you haven't already done so.