For those that don't know where to post, start your own thread to get advice. This isn't the place to start your story. Its a sub folder. Help is here, if you can just hit "The Newcomers" and in upper left corner hit "new topic" I believe.
Start with your ages, time married, kids if any. Your situation and why you think your marriage is where it is.
Know that you will be on moderation for a time, meaning your posts wont show up until approved, it will stay that way until you've reached a certain post count. Initially that can take 2-5 days. Be patient with the process, the help your looking for is here. Read and post on other people's thread to spead the process up, it also helps that other people see your thread and will come over and post on yours.
People here want your marriage to work, will give you the tools to hopefully help that process. Theres no guarantees, but you have nothing to lose in trying.