SMTP Email Setup from 3rd Party provider

Hello, i woild like to know the steps or the setup guide on what DNS i have to put in my Host ( VPS ) also i am using cloudflare.. i need to made any changes to my WHM ? I have a SMTP Server and PHPMailer... i want to connect my Email packet from a 3rd party company to my SMTP server... i got some DNS from my email compnay i have add themto cloudflare but the SMTP dosent worked!