Why don't my bombs break walls?
The only way that wall would not blow up is if you are playing the second quest. If you are playing with the name ZELDA or have beat the game once, you are playing the second quest.
In the Second Quest, all dungeons are rearranged and often found in different locations.
Because everything is rearranged in the second quest, guides for the first quest will be of less help.
Here's a visual guide which describes the heart container locations more or less as follows, with further description adapted from this wakthrough:
First Quest
From Start, go four screens to the right. Use your Bomb's just left of the pathway leading up to find a secret door which leads to a Heart Container.
From the start, head right four spaces, up five, and right one to the desert. Blast the right side of the large rock to reveal this location.
From the start, head right one space, up three, and left one. Burn the fifth bush from the right to reveal a staircase.
From the start, head right eight spaces, up four and use the raft to head up once more. You'll soon find a door which leads to the Heart Container.
From the start, head right eight spaces, and up two. Use the stepladder to climb to it.
Second Quest
From the start, head up one space, left five, up one and down on the left side, left one, through the Lost Woods into the graveyard and up four. Push a gravestone with the Power Bracelet to reveal a staircase which leads to the Heart Container.
From the start, head right four spaces, up four, and left one to the lower left of the dessert. Use the whistle to reveal the hidden staircase.
From the start, head right one space, up five, left one, up one, cross the river, and up one, and finally right one. Play the whistle to reveal the staircase.
The same as the first quest. From the start, head right eight spaces, up four and use the raft to head up once more. You'll soon find a door which leads to the Heart Container.
The same as the first quest. From the start, head right eight spaces, and up two. Use the stepladder to climb to it.
The heart container location for the second quest for the location on the top line of the map is actually two screens to the left from where it is listed.