How can I ask for a VA disability appeal?

I am currently receiving 30% VA disability rating I received in 2007 for PTSD. I am seriously thinking of my situation worsening everyday. My marriage and close relationships are on the brink of collapsing. I have started on medications and am more anxious than ever. I would like to appeal to see if I can get a higher rating but am not sure where to start. Can any one help me with my situation? Has any one here gone through the same situation? I would REALLY appreciate it if any one can help me out. Thanks to all in advance!