Convert Zebra Printer Label Files to ZPL(II) code

I need someone to convert two .lbl files to ZPL code, there are many variables in the labels, and I set them all to the word VARIABLE. We are developing an application in android, and currently we are sending the labels to an RW420 printer as image files, and it takes a long time for the information to send across, so I would like to convert to ZPL to save time. I would need a short explanation on how to insert the variable information into the ZPL code. The labels use 128 barcodes.