Deburring

Use a carborundum or diamond stone and drag it from the Snowboard's Tip to the Tail of the edge. Repeat the movement until all nicks and burrs are gone and the edges are smooth again.

Base Edge Tuning

Tuning Edges is best done with a file. Start off with the base edge of the Snowboard. Still, take care with filing. Make sure not to file the base of the board and only file as little as needed.

Side Edge Tuning

After filing the base, you can file the side edges. Use a small file so you won't have a hard time filing the Sidecut of your Snowboard. Special edge files will make it easier to determine the angle that you are filing in. When it comes to tuning your edges you have a couple of options:

Base edge angle is 0, Side Edge angle is 90 degrees. Most boards come from the shop with these angles leaving you with enough options to change it.
Base edge angle is 0, Side Edge angle is smaller than 90 degrees. This gives you a sharper side edge which will increase your grip on turns in snow. This setting is handy for icy conditions.
Base edge angle is larger than 0 degrees, Side Edge angle is 90 degrees. This dulls your side egde decreasing your grip but increasing your boards grip. It will also make it easier to make turns.
Base Edge angle is larger than 0 degrees, Side Edge angle smaller than 90 degrees. By tuning both edges you can actually maintain the 90 degree in your edge but with a repositioning. Some people find that in this way, they can profit from both effects: more speed and easier turns.>

Smoothing the Edges

Once all the basic deburring and edge tuning and detuning has been done, you can use a whetstone to smoothen out all the edges.

(source : http://www.abc-of-snowboarding.com)