Welcome page margin issue

Hello all. Forgive a newbie’s basic question, but I have googled for two days and cannot figure out how to adjust the text margins on my welcome page in Oprum. The default has the text going right up to the left and right margins of the white border box: http://www.shipgeek.com. I’d love to add some breathing room to this on both the left and right sides. Also, the heading at the top “Welcome Aboard” should adjust to the same new margins. Any experts out there willing to help a neophyte? Thanks in advance.