This image is not available online. It has been microfilmed and can be found at the Family History Library. If you have a Family History center near your home, you can order the film sent there for you to read and copy.
Harrison Co,, MS marriage records appear to be on 36 reels of film. Judging from the date given 7 Sep 1875, you would want either Marriage Bonds (1869-1878), which is film no 887961, item 1 OR Marriage Records Volume 6 (1870-1878) which is film no 887949. You might want to order both just to be sure.
Hope this helps