Well the general idea (which you can then implement with the help of the tutorial I suppose) for both would be:
1. Make 2 common events, one for your attacks, one for your hp bar.
2. Swarm your maps with parallel events that trigger them
3. The hp bar is simple, you can use the Zelda style by pretending every X hp is 1 symbol or half a symbol
So simply make a symbol, say a heart and make it so that for every X hp the event will draw on the bottom left one of those symbols, every run of the event the symbols will be erased and redrawn
You probably want to put a "wait 1 second" command at the end of the event.
(you can also use pictures for the images as suggested in the tutorial)
4. For the weapons it's a bit trickier, first the attacking event - you use "if button S was pushed" then you draw a picture of your shot (Fireball, arrow, you name it) and trigger an event that will move it to the direction your character shot it. (and of course just as easily remove the picture after X cells)
[Note that this is harder than in the guide, the guide suggests you simply hit regardless or so it seemed to be in brief reading, What I am suggesting here is to actually allow real-time dodge]
5. This is the tricky part, actually dealing damage, you can make your parallel event check if the image is touching any enemy on the screen, the reduce it's hp or something and make the shot disappear.
Or you could put such handler on every shootable NPC on the map.
When their hp goes to 0 (a variable) set a flag that makes them disappear.
6. Now you make an arrow item... well pretty much get an arrow sprite (you'll shoot it too) and make a misc item called arrow, nothing special.
7. Scatter events that have "upon hero collision" trigger or "when hero talks to..." or whatever, trigger a flag that will make them disappear from the map and add 10 of those said arrows to your inventory
8. back to the shooting thing, every time you shoot an arrow remove one from your inventory, if you cannot simply don't shoot (condition the whole image appearing part with the successful removal)
9. just like the hp bar either make arrow symbols or number symbols or whatever you feel like.
Hope that made it a bit more simple.