He is talking about your cover pic on you timeline on fb
I think your cover foto shall tell something about yourself
For instance I love jokes and quotes and I am madly in love with awesomeness, so my cover pics are jokes, and SPAM I have a cover that says "I'm Awesome"just white on black, no fancy things or so
but if you like cars, then put a pic of your own car (if it is worth a little), if it is a piece of junk or you don't have 1, then put a pic of your car of your dreams
If you are a huge fan of a celebrity or band then put them as cover, if you love your sport or hobby then put that up. If you are good then you comebine it. As said I love fun stuff, but I also love to workout, så I have also had cover pics with workout jokes, where the joke intentions have been to put workout as something better then the other that was mentioned in the joke
Hope it can help you a little
PS: I suggest you switch cover pic at least every 2 month, but that is just me