Minor assault charge over 2 years old which I received a fine how will it afect work permit for canada??

You might want to call the Canadian embassy closest to you, you might not be able to get the work permit due to the charges but if you paid a fine maybe you don't have a record... this is somewhat case specific. Do you know if the charges show up on a police background check? Being upfront and admitting the problems from your past to the embassy might help.

Don't know if true or not but I heard Canada does not accept anyone with a felony but you didn't specify if it was or not so I don't know if it applies to you.