I need a step by step procedure to change the oil on my 2003 Yamaha 250 YZF

This engine holds one quart of standard Yamaha YZ 250 engine oil. The oil filter is located on the rear of the crankcase behind the suspension spring. The oil filter looks like a small metal can that is screwed into the top rear of the crankcase. On the bottom of the crankcase is the plug that will need to be removed to drain the oil from the crankcase. Anyone who owns this model dirt bike can complete this job in about 10 minutes.
Read more: How to Change Oil and Filter on a Yahama 250F ' eHow.com http://www.ehow.com/how_6574975_change-oil-filter-yahama-250f.html#ixzz1hECQRtAn

As much as it takes to come up on the oil stick between the marks. Use the proper oil ONLY

I have listed a link to a site that I think will you help you. http://www.thumperfaq.com/oil_change.htm#Proc%2003

try this
http://www.mxguy.com/motorcycle-maintenance/2003-yamaha-yz250f-service-manual_01-16-2008/

My best advice is coming from home mechanics. I work on my own bikes. I suggest getting on ebay and buying a chilton manual this will take you step by step on everything on your bike you will ever need to do. They are like 20 dollar. But it also should be in the back of your owners manual.