Welcome to the GE forums,
Most questions you will have to begin with have been asked and answered. Also many things are covered in the tutorials in the Help menu of GE. Look at the platform game tutorial for jumping. You may encounter a problem with your character doing a double jump, you can do a forum search for it here as the problem has come up often. Also, do a search for your health bar question, some people have posted GE files and code as examples.
Jumping:
http://game-editor.com/forum/tp-4287-Ho ... jump-.html