Parameterized FizzBuzz
Some quick remarks   


variables should be named using camelCase casing  
avoid declaring multiple variables on the same line to improve readability. 
don't trust the users of your app! Never trust them! If you think, hey they can read and follow instructions you will get into great pain. Always check that inputs are valid. That beeing said you should use int.TryParse() instead of Convert.ToInt32()  
method arguments should be named using camelCase casing as well.  
let your variables have some room to breathe (see the % operator)  
don't use abbreviations for naming stuff. In a few months you won't know what they are about.  
comments should explain why something is done in the way it is. Let the code speak for itself what is done by using names as descriptive as possible.