As NicC said, this is not properly a JCL question. JCL, by itself, cannnot manipulate data in any way.
More likely, it is a sort issue; I believe both DFSORT and Syncsort have an OUTREL control of some sort. Another possibility is to use IBM data set utilities. I think both the IEBGENER or IEBPTPCH utilities can be persuaded to edit your data in the way you want, though neither utility has an OUTREL control by that name.
The C'...' notation is for character constants (there are other types you can look up). The X is a blank, 3X would be three blanks. There is others of those as well (see if you can find what Z does. 1,6 takes the first six from the input, and places them in the next available six from the output. 8.3 is similar.