Before using an oil stone you'll need to damp it. Either water or oil will be file, but oil is usually preferred as it avoids creating problems to parts of the knife if you don't dry it properly. The stone will get the water or oil, and become damp. If need to keep the stone costantly damp when sharpening, so you might need to damp it more than once.

To polish the blade, pass the blade along the whole stone, with an inclination of approximately 7 degrees. Start from the left side of the stone and, while passing the blade on the stone, move it towards the right. After one pass, you need to do the same for the other side of the knife, but following the oppisite direction: start from the lower right corner and proceed towards the topp left one. Carry on with constant speed and inclination.

Perform this operation various times, until the blade is sharpened. With a raw stone you'll need about 10 passes per side of the blade, while with a fine blade you'll need 20, 30 or more. The more the stone's grain is file, the more passes you'll have to perform, and the best sharpening you get.