Example shots: Let's assume you're always shooting right. It will make it easier.
Example 1:
Wind is like this: 
The enemy is at half screen, or maybe a tiny hair past it.
Step 1: For half screen (15/30 parts) the landmark angle you should
have memorized is 75. This is your 0 wind angle.
Step 2: This wind direction is down+forward. Looking at the windchart, the wind factor for that direction is .25.
Step 3: The wind's strength shown in the blue circle is 6. So multiply .25 by 6 and you get... an ugly fraction, 1.5.
Step 4: Normally, since this is a blue wind factor, you raise your angle by the answer you got in step 3. But you cannot raise your angle by 1.5... you must raise either 1 or 2 degrees. So what's the correct answer? Well, this situation is common so you must learn to deal with it. There are several ways. You could raise only 1 degree, knowing that the shot would fly a little past half screen. Not by much, just half of an angle. Since I already noted the enemy is a tiny hair past half screen, then angle 76 is probably ok to use. The other solution is to walk backward a little bit. You know the shot will fly a few pixels further than you want, so just walk a few pixels backward and it will be perfect. Or... you could choose to round up and raise your angle by 2 degrees instead of just 1. Then your shot will be half an angle short. To make sure it doesn't miss, you could add a tiny bit of power or walk forward. My favorite solution when I get fractional angles is to round down, always, to the lower angle. The lower your angle is, the safer it is... usually.
Step 5: Assuming you chose angle 76, the only thing you must do now is choose power.
It's 2.4 bars for most shots, and that includes half screen distance shots.
Final answer: use 76, 2.4 bars.
Example 2:
Wind is like this: 
The enemy is at 2/3 screen distance (20/30 parts).
This wind factor isn't shown on the chart, but it's very close to wind pointing directly against you, which has a factor of .6... so we'll treat this as a .6 wind factor.
The wind strength is 9, multiply 9 and .6 and you get 5.4... we'll round down, as always, and call it 5 angles.
Our basic angle for a 2/3 screen shot is 70... so now we'll lower by 5 angles to 65.
Here's the tricky part. The power for this distance is normally
2.4 bars, but you're gonna add just a hair of power. Why? Because
instead of lowering 5.4 angles (from the math you did earlier) you
only lowered 5, so you expect the shot to land a little short. Also,
when shooting long distance (near 1 screen), down wind and opposite
wind will hold your shot back more than you expect, and sometimes
you have to add some power to compensate for that. So the power
level must increase a little bit.
Final answer: 65, 2.45
Example 3:
Wind is like this: 
The enemy is at 1/3 screen distance (10/30 parts).
The 0 wind angle for this shot is 80. Remember from the previous
example that you can use the .6 wind factor, since this wind is closest to that.
Multiply 24 by .6 and you'll have 14.4... so you'll lower 14 angles.
The angle goes from 80 to 66. Once again, because your answer was a little
more than 14, your shot might come up short, so add .05 to make your power
2.45 instead of 2.4.
Final answer: 66, 2.45.
Example 4:
Wind is like this: 
The enemy is at 1 screen distance (30/30 parts).
The rule on the chart for vertical wind is to change power, not angle.
From before, you might remember the rule says to reduce .1 bars
for every 7 wind. So in 14 wind, I'd reduce .2 bars. This wind is a bit
more than 14, so I'll reduce .25 bars.
So you'd think the final answer is 60, 2.25 bars.. but that might fly a bit far.
There are two reasons you should reduce power even more:
1. If you look closely, you can see the wind isn't pointing perfectly up, it's
also pointing forward a tiny bit. If the wind were weak, that wouldn't matter.
But for strong wind near 20, that little bit of 'forwardness' will make it fly
further than you expect.
2. Remember that for long ranges, upwind and downwind have greater effect.
One screen distance qualifies as a long range shot.
So the real final answer:
60, 2.2 bars.
Example 5:
Wind is like this: 
The enemy is at 1/6 screen distance (5/30 parts).
Your basic 0 wind angle for this shot is 85. The wind factor for this wind is about .6, so in 10 wind you need to raise 6 angles. But you can see there's a problem - You cannot add 6 to angle 85 and get angle 91. So what you do is raise your angle to 90, then go one more angle away from the enemy (one more angle 'left') to get angle 89 in the other direction. So your shooting angle is 89 (backwards) with 2.35 bars of power. I actually would use a bit more power because the wind is pointing downwards a bit, it's not pointing exactly in the forward (.6 factor) direction.
Now is a good time to mention that there are some issues that can occur when your angle gets too high or too low (or backwards, in the above example). I'm gonna list those difficulties right after the next section.