@testaaaaa Giving the young man an opening at this stage is less than extremly modest. You don't see the difference between 18xx and 13xx. Giving him an opening is leaving him in delusion.
Was die positiven Kommentare angeht möchte ich mit einem Zitat antworten: Jeder Quacksalber kann seinen Wohnwagen mit Dankesschreiben tapezieren. (E. Bleuler)
What would you have us do, then?
You're 18xx, not 13xx. With 18xx you should know from experience and ranting with other chessplayers something about the openings you play. So staying to those openings and learning about the middlegames and endgames resulting from this is probably the way to go.
But: I'm only 20xx FIDE. You should ask someone stronger, at least 22xx. If I would have to train a junior player with dedication to chess I would recommend from level 14xx to look out for someone stronger and stop the training from level 16xx (if there aren't special circumstances).
To say it clearly: Opening training IS important. But it must fit to the level of the trainee. It starts with some principles, then open games, gambits. Then you should have reached 14xx and here I hand over to someone stronger.
Well, that sounds reasonable.
Against d4 and e4 just play respectively d5 and e5, and then defend what the opponent is attacking. Get your pieces out, castle and try to put some pressure on some of opponents pieces to make it harder for him to develop quickly.