Briggs & Stratton won't start?

I have a Bolens riding mower with a Briggs & Stratton 17.0 engine, It will turn over until it hits the compression stroke then stops turning over. I was told the valves need to be set because the compression release isn't working or set right. The parts house I went to to buy a new starter told me this and said I don't need a starter, just adjust the valves. How do I set the valves on this engine?

Thanks.