Are we talking about the same thing? My understanding was
1) OP asks about getting his blink going at 2 Hz rather than 1Hz
2) CrossRoads says "change the delay to 1/2 as much"
3) cjdelphi shows the actual code (having replaced 500 with 250)
4) MAS3 objected to providing the finished answer (after all, now it is just a matter of typing in the answer without understanding anything)
5) cjdelphi said was already there
6) I agree with MA3/CrossRoad, and disagree cjdelphi. I also think "change the delay to 1/2 as much" is a BIG hint, but for the simple question it is hard to more subtle without starting to speak in riddles.
So before 3) above the answer was not on the page, which is what I agree with MAS3 on.
But - it is a tiny matter. I have not investigated if any of the posters do what the do often.
I do teach (occasionally; professional courses in specific software applications) and whenever a student asks a questions that is not a simple factual one, I do try and think of all the misconceptions that prompted the question.
In this case, I might have first checked if the student realized that
Period(frequency) = inverse-of interval(duration). By then asking him/her about what defined the duration in this code, they might have come to the conclusion that the delay needed to be shorter. Secondly I might have asked what the OP meant by "PWM" at the end? (I still wonder why that was an afterthought in the question - there may have been a total mixup in the students mind - due to the course material - between analog and digital write, a blinking LED and a dim LED (which is blinking to achieve the effect...) )