So here's how I did it:
1. Since this pattern is based on BurdaStyle's Lydia Top I cut out my pattern as normal and kept the front piece handy. Although an already made/purchased top would do just fine I think.
2. I measured out how long I wanted the ruffles to be on the top and did it kinda like this. (By the way yes I did go to the effort of finding a paint program online to scribble, save and download this pic to my laptop, which was actually kinda fun)
3. I cut 7 strips in the above lengths with a width of about 2 centimetres and sewed right down the centre before ruffling them. (Don't worry if you don't know how to do ruffles this was my first time and I just copied this great tutorial here at A Pretty Cool Life)
4. One by one I evened out the ruffles of each strip and pinned it to the top, sewing each strip on before attaching the next. I did it this way because I positioned them quite close together and the pins were fighting with each other. If you're a savvy sewer you could probably pin them all at the one time and sew away.
5. Once all your strips are attached and sewed on you're ready to sew up the rest of the top!
** Since I'm new to sewing I thought I'd share some last thoughts on this top with you. Firstly I've chosen to edge the neckline differently than the original pattern on Burdastyle because it neatly tucks away the edges of the ruffles. Secondly if I were to make this top again I would make sure I paid more attention to the bottom of the ruffles. You can't really tell from these photos but most of the ruffles simply end in the square bottom of the strip sitting flat against the top which looks ok, but in retrospect I would have rathered to bunch the end more or curl it under slightly so it didn't look so amateur.
So for my next project I have my sights set on making a Henley style top possibly incorporating a ruffle. I'll see if I can find a tutorial or possibly muddle my way through it and hope for the best!