How did the English Civil War change england's government?

And

What was the significance of the Long Parliament?

The government was changed because it was established that no monarch would ever be able to rule independently without the consent of the Parliament. This meant that the absolute power of the monarch was heavily reduced and the parliament held the supreme power.

The significance of the long parliament was that they were all gathered around ideas that supported popular liberties and were highly progressive for the time and since they couldn't be removed then it is believed that their acting enabled Britain to become the greatest force in the world.