Before you begin, please refer to Tutorial - Making the .tweak File Modifiable, which teaches you ow to make a .tweak file modifiable. You must be able to do this for all of my tutorials.
 

Stinger Missile Folder Location
We must first know the location of the Stinger Missile.

1. Navigate to C:/BF2_Directory/mods/bf2/.
2. Open Objects_Server.zip.
3. Open Weapons/Armament/Missiles/igla_9k38/.

Explosion Damage
First, we will modify the Explosion Damage of the Stinger Missile.

1. Open igla_9k38.tweak.
2. CTRL + F and type "ObjectTemplate.detonation.explosionDamage".
3. Change the number (75) after explosionDamage to a number of your choice (do NOT exceed 3000).

Explosion Radius
Next, we can modify the Explosion Radius of the Stinger Missile.

4. CTRL + F and type "ObjectTemplate.detonation.explosionRadius".
5. Change the number (4) after explosionRadius to a number of your choice.

Damage
Though we did modify the Explosion Damage of the Stinger Missile, we must still modify the Damage of the Stinger Missile.

6. CTRL + F and type "ObjectTemplate.damage".
7. Change the number (300) after damage to a number of your choice (do NOT exceed 3000).
8. CTRL + S or File>Save.
9. Close igla_9k38.tweak.