Setting up an Email Server

Hello everyone. I am new to this forum and I don’t know where I should post my problem so I am leaving it to the moderators to move it to the appropriate section.

So I need expert help from a kind soul who is an IT expert and who has experience in Mail server setup through vps and domain. I am not a techie but I have tried setting it up by buying a step-by-step guide but it doesn’t work. So I need help from an expert who can overlook what I did and suggest what can be done next.

Anyone here who can help a brother in need? I would be forever grateful.

Thanks.