Small Engines (Lawn Mowers, etc.): Lawnmower will not start, spark plug gap, spark tester

Question
I have 6.75hp Craftsman lawnmower Model# 917.378493. It worked fine the last time I used it about a week ago. This morning I filled it with gas and tried to start it. Nothing. I filled the oil and changed the air filter. It still will not start. I was told to check the spark plug but I'm not sure how to do that. Is there anything else I can try? Where do I go from here? Thank you.  

Answer
Darcy
To check the spark you can use a spark tester or take out the plug and hook it up to the spark plug boot (coil). Rest it on the engine so that the end touches a part of the metal, Crank it over to see if there is a jump between the spark plug gap. If there is good spark you have one thing solved.Then you need to make sure you are getting fuel. Try spraying some carb cleaner in the intake of the carb,it it tries to start then you have a fuel problem.

Thanks