didnt u get an instruction sheet which comes with it wen u bought the filter? u just need to fill a cup with plain water big enuff for the filter to go in but only fill it up to just below the plastic casing, let it rest for about 10-15 mins den gently shake the filter a bit for the dirt to come out, repeat this process for about 3-4 times with clean water each time and ure good =)
oh and leave to dry for at least a day and DO NOT add any oil as the filter does not require any oil.
this is wat i recall from my instruction sheet but if any1 else have other methods den please share.