Sorry, I'm not on miiverse often. You can type in BGFILL and hit the magnifying glass at the top right to look at the command's syntax (how to use a command)
Make your sprites. Save the sprites. In your program, write LOAD"GRP4:(name of sprite sheet)". You then can write "SPSET 0, (sprite #) to place the sprite.
Have two variables to store the health ints. Then, write an IF statement to check if the player's attack hits the enemy. If so, change the enemy's health to it minus itself. The GUI can be a FOR statement that prints out many '■'s at a certain location.
First, save your sprite sheet. Then, in your code, say:
SPSET 0,Sprite #
Change the 'Sprite #' to the sprite's ID, then there should be a sprite in the top left.