how can i learn WordPress
Download it and play around with it?
Or you could buy a book - for example:
Take an online course: https://learnable.com/topics/search?q=wordpress
Search for tutorials: http://www.everyclick.com/search?keyword=Wordpress+tutorials
Then, if you have any specific questions which haven't been answered, feel free to come back here and ask. Meanwhile, I'm closing this thread.
In addition to TechnoBear's great suggestions, don't be afraid to spend time with the Codex. A bit intimidating at first, but with time it will become a valuable asset to you.