I'm guessing the granules are dried crushed seaweed (seaweed meal). They won't dissolve, so use it as you would blood, fish and bone. I scatter a handful of both over an 1 metre area before planting.
Using seaweed extract as a foliar or soil drench - once every 1 or 2 weeks
It's not a fetilizer (though does have some nitrogen) but it has lots of stuff that help strengthen plants and make them grow better and resist disease