If using dried dates: soak in warm water for 10 or so minutes until soft again.
If using fresh dates: make sure the pits are removed.
Put your dates into a blender or food processor with enough water to begin blending. I always start with just enough water and then add more as needed. It does thicken as it blends so you may need to add as they chop up.
Blend until smooth and creamy.
Pour into a jar and store in the fridge. It keeps in the fridge for about a week and a half. This also freezes very well, so making in bulk is very easy. Just portion into jars, store in the freezer, then remove and let thaw as needed.
You can add additional water to make something more like a syrup, depending what you want your sweetener for.