Just use it!
Water based filler such as Modostuc can be used for a wide variety of uses.
For holes or cracks on walls or furniture, you can use wood filler to repair all of the little imperfections on your object.
Just use a small trowel and apply it where necessary, let it dry and it's done!
You can mix wood filler with pigments such as oxyde dies or universal colorants to get the colour of the filler closer to the wood one,
or varnish all together at the end of the job.