Its very simple .I dont know what kind of fish you want to fillet but here goes nothing .
*step 1
Give the fish a quick wash in cold water .
*2 Lay the fish on its side on some news paper over a cutting board .
*3 Make sure your knife is sharp
*4 Make a cut just behind the pectoral fin , thas the first fin along side right behind gills . Make an inward cut until you hit the backbone .
*5 Turn your knife around cut from the first cut all the way down the backbone to the tail .
Do this on both sides
*6 Lay your fillets down put the head and guts in garbage ,
*7 Take your knife from the Tail but angle your knife and pull the skin back then you will have a skinless fillet .
For trout Cut the head off cut the belly openall the way to arsehole pull out the guts , and good to go .
Here is a really good video .
http://www.youtube.com/watch?v=VyNSwgRq3OE