Fuel Rail Fitting

[cebra]

I have done a lot of searching but cannot figure out for sure how these 6an to 3/8" and 6an to 5/16" fittings connect to the fuel rails. Below is a picture of a return style rail which I have and the other picture is the 6an fitting I want to use. My questions are, where do these male fittings connect to the fuel rails and what do I need to remove from the existing system as shown below (less the blue push on fitting)? Thanks.