Using a Brush: Put lots of stain on the brush and apply a thick , even coat. One coat will do the job but if the wood is a contrasting colour or very weathered a second coat can be put on.
Using a Sprayer: Pour the stain into the sprayer. Pump it up or turn it on and start spraying. For an even finish use long, sweeping arm movements and move along the full width of the panel. Drop down and do the same again going over where you have already sprayed by 50%.