cron job for m2e pro extension in magento

I need someone experienced in m2e pro plugin for magento to do a cron job for me, a simple inventory sync. This is a very fast job should take less than an hour. I simply do not know ANYTHING about "cron jobs". I am using a VPS server with cPanel VPS optimized software. I have attempted to setup the cron job myself, and it works sometimes but not all the time. It may already be setup and working properly, I might just need someone to tell me that it is indeed working properly. I need the cron job to update every 5 minutes, an sync the inventory numbers, and ebay orders with magento.