If the flaxseed appears to be small brown pieces (like 'hundreds and thousands') then it has to be ground before it can be used. I use an ordinary food processor to do this - the same attachment for grinding coffee beans or creating sugar powder. The result is a light brown powder.
This should be stored in an air-tight container to prevent oxidation. The ground seeds shouldn't be kept for more than a week or so as they lose their effectiveness the longer they are kept.
There is no need to wash or cook the seeds. I add the powder to my morning yoghurt - it's supposed to help lower cholesterol levels amongst other properties.
I have heard that the stone of an apricot contains cyanide - but not flaxseed (otherwise I wouldn't be here to be writing this!).