How to move down a division in CSS for wordpress website?

Sir/mam I am a beginner, please help me how to move down a division using additional CSS for a WordPress website,

I want to put down related posts division just below the answer division

I tried them with inspect element but I dont know how to imply those change in website file... I had tried relative positioning but it does not work, maybe I had applied it wrong...

Please answer in detail, I am very confused

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