Thinly slice the cucumber - traditionally this is done with a Swedish-style cheese slicer but you can also use a mandolin or just a sharp knife. Use either two bowls of around the same size or two similar plates with a relatively deep rim for the next step.
Make a layer of cucumber with some of the slices of cucumber in a bowl or on a plate. Sprinkle over salt then add more cucumber, then more salt until you have layered up all. Place the second bowl or plate on top of the cucumber slices and press down - you can weigh it with eg cans of food. Leave to allow the cucumber slices to drain for around 10 minutes or so.
Meanwhile, combine the water, vinegar and sugar. You can either mix in a small pan and warm, stirring, to help the sugar dissolve or place all in a microwavable bowl and warm for 10 second intervals, then stir, until sugar dissolves. Leave to cool then add the dill.
Drain off the liquid that has come out of the cucumber slices. You can also squeeze them gently to release more liquid but take care not to break up the slices. Place the drained cucumber in a bowl and add the vinegar-dill mixture and stir gently. Cover and refrigerate for at least an hour, or ideally 2-3 before draining as you serve them.
Video
Notes
Note video and photos show a half quantity to the recipe quantities, but the method is exactly the same. Just multiply up or down quantities to suit what you have and need.