Your best guess is probabally where it's leaking from. If it is leaking there, you need to try to tighten it a little more. Isn't it nice how they give you all kinds of access to these fittings?

If you don't have a line wrench, it will be next to impossible to get it tight enough. Even with a line wrench, it will be miserable to try to tighten it because the fender skirt gets in the way of the only area that you can access it. The real tool you need to tighten the fitting is a crow's foot line wrench, so if you have to go buy a tool to do the job, get a crow's foot line wrench.