I bought a model 19 from the Pawn shop around Christmas. It finally warmed up enough to go to the range.

Now... I'm not the best shot, but this puppy is WAY off.

I though bullets fell when shot at distance. These were 3 feet high at 50 yards.

How is the best way to sight in my model 19?

Does ammo choice play a significant role in this process?

I enjoyed shooting .38 Special +p ammo with an occasional chamber full of .357 thrown in for good measure.

Is there a youtube video, PDF or web site that describes adjustingt he sights?

Mostly I envision this as a range, IDPA, and home defense weapon.

I would start with shooting at a closer target. Then screw the sight screw clockwise until you start getting a better pattern.

Can't point you to any videos, but adjusting the sight is fairly easy when all is said and done. You just need to remember to move the rear sight/blade in the direction you want to move the bullet impact.
In other words, if you want to lower the point of impact, just lower the rear sight. You can experiment with the elevation screw, move it counter clockwise and clockwise to see if it's raising or lowering (just watch the sight blade assembly from the rear). The same with the windage, just adjust the screw counter clockwise and again clockwise and watch the sight blade move side to side, again - adjust the rear sight/blade in the direction you want to move the bullet impact.
Two other points, bullet weight will effect the point of impact, a heavier bullet will generally hit higher on a target than a light bullet.
Last, my recommendation is to move your targets close, start at 10-15 yards, sight in and move back and adjust accordingly, my belief is that 50 yards is too far away to get to know how a new gun shoots. Too many variables, shooter, ammunition, where the sights were set by previous owner, etc. Get it sorted out closer and then move back to where you want to shoot.
50 yards is too far.

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.............SmithNut

Here is the method that works like a charm for me. Take your gun and visually center the blade of the rear sight in its slot. Then turn the rear sight all the way to the bottom.
Set a target out at 7 yards and rest the butt of the gun on sandbags or whatever soft object you have. Fire perfect single action shots and adjust the sights until they are dead on at 7 yards. You are done.
You may have to make a slight adjustment at 25 yards. Pretty much though if you aren't hitting it is you not the gun. If you are moving your sights around at 25 and can't get the gun sighted in, it is not the gun. Fifty yards the same thing.

Heck yeah! Ammo choice plays a HUGE role in accuracy at 50 yards.
What bullet weight were you shooting? Do you know the approximate velocity?

Not trying to knock anyone else's advice here, but the following is something to remember when trying to adjust your sights on a your handguns-

A lot of folks aren't aware of this, but NEVER rest the butt of a handgun on anything, especially anything hard like a benchtop, but even sandbags will be a problem.

While it may not affect your group size or POI at 7 yards due to the very close range, it'll definately start to show up out at 15-21 yards and beyond.

The reason is simple. When you fire the gun, the gun starts to recoil before the bullet has left the barrel (the same reason heavy slow bullets hit higher on target than lighter faster ones with the same sight settings). The gripframe will actually recoil away from any surface it is in contact with, including even something as soft as sandbags. Then when you shoot standing up, and offhand, and your POI is noticably different, you start wondering what you are doing wrong and second guessing yourself and your shooting ability, or think that somehow your sights got out of whack. That does nothing to help build your confidence and skill level.

The correct way to do it is to rest the frame right in front of the trigger guard (preferable), or the very first couple of inches of the barrel right in front of the frame on some type of pistol rest or sandbags, and support your wrists/hands on another rest, or another set of sandbags. That will much more closely simulate the hold you have when standing or shooting offhand.

Actually, the proper way to bench rest a hand gun is to hold the gun in both hands and rest your hands on the support, without letting any of the gun touch the rest.

Do as Moosedog and the others say. Sight in at 7-10 yards. A slower bullet, such as .38sp. (vs. .357) will print higher.

I agree with you Leonard and I shoot the same way that you suggested, but.........as stated by the OP he isn't the best shot, and anyone else who is new to handguns or doesn't practice regularly will have much more success using the method I described above because it helps eliminate human error and wobble by providing a way to steady the firearm as much as possible to adjust their sights without the rest altering POI rested from POI standing.

I agree WITH SMITH NUT START 10 YARDS TRY TO KEEP THEM IN A 8 INCH CIRCLE THEN MOVE BACK TO 15YARDS