How do I make a steampunk fantasy world?

I want to create a word with elements of steampunk, magic, and fantasy. The only thing is, I don't know how. If anyone has read His Dark Materials or The City Of Ember, I'm trying to go along the lines of that, but how do I also stay away from copyrighting His Dark Materials or The City of Ember?

Just write the book and don't worry about copyright issues. When you have finished, go through the book and edit all the bits that resemble them out.