Converting Collar neck to Round Neck: Step 1: Remove the stitches on the collar of the dress. Step 2: Take off the collar. Step 3: Measure the Neck, mark and cut the deep you want at the front and back of the neck. I would suggest you to not touch the back neck and to not deepen the front neck more than 5.5". If you would like go 6 or more, you should adjust the shoulder width accordingly to avoid shoulder slip and for a better fit. Step 4: Open the bias tape, pin the good side of the bias tape facing the good side of the neck. Step 5: Stitch along the curve of the neck. Step 6: Steam iron the stitched area.