Alright so I'm getting the hang of this "modding" if we can call what I'm doing that, thanks to some very helpful people. However now I have moved on to making new abilities. My first try was to make a MissileBarrage equivelant, actually the same, only difference would be that instead of missiles, it would fire that ghostly looking missiles that the Advent Starbase uses as its top weapon upgrade.
 
What I did was to copy the files:
AbilitiyMissileBarrage
BuffMissileBarrageFire
BuffMissileBarrageHit
And changed them into:
AbilityGhostBarrage
BuffGhostBarrageFire
BuffGhostBarrageHit
Next, I went into AbilityGhostBarrage and changed
"buffType "BuffMissileBarrageFiring"" into "buffType "BuffGhostBarrageFiring""
and then into BuffGhostBarrageFire and changed
"buffType "BuffMissileBarrageHit"" into "buffType "BuffGhostBarrageHit"".
Now to change the effect I want to change. In BuffGhostBarrageFire I made this change:
    weaponEffectsDef
        weaponType "Missile"
        burstCount 3
        burstDelay 0.080000
        muzzleEffectName "Weapon_TechCapitalMissileHeavy_Muzzle"
        muzzleSoundMinRespawnTime 0.100000
        muzzleSounds
            soundCount 1
            sound "WEAPON_TECHCAPITALMISSILEHEAVY_MUZZLE"
        hitEffectName "Weapon_TechCapitalMissileHeavy_Hit"
        hitHullEffectSounds
            soundCount 1
            sound "WEAPONIMPACT_MISSILEHEAVY_HITGENERIC"
        hitShieldsEffectSounds
            soundCount 1
            sound "WEAPONIMPACT_MISSILEHEAVY_HITGENERIC"
        missileTravelEffectName "Weapon_TechCapitalMissileHeavy_Travel"
        missileStartTurningDistance 300.000000
        missileSlowTurnRate 0.708997
        missileMaxSlowTurnTime 4.000000
To:
    weaponEffectsDef
        weaponType "Missile"
        burstCount 3
        burstDelay 0.080000
        muzzleEffectName "Weapon_PsiSpirit_Muzzle"
        muzzleSoundMinRespawnTime 0.500000
        muzzleSounds
            soundCount 1
            sound "WEAPON_PSICAPITALSPIRIT_MUZZLE"
        hitEffectName "Weapon_PsiSpirit_Hit"
        hitHullEffectSounds
            soundCount 1
            sound "WEAPON_PSICAPITALSPIRIT_IMPACT"
        hitShieldsEffectSounds
            soundCount 1
            sound "WEAPON_PSICAPITALSPIRIT_IMPACT"
        missileTravelEffectName "Weapon_PsiSpirit_Travel"
        missileStartTurningDistance 300.000000
        missileSlowTurnRate 0.708997
        missileMaxSlowTurnTime 4.000000
 
Lastly I went into the String folder and into English and made these changes and additions:
NumStrings 5361 => NumStrings 5363
StringInfo
    ID "IDS_ABILITY_GHOSTBARRAGE_NAME"
    Value "Ghost Barrage"
StringInfo
    ID "IDS_ABILITY_GHOSTBARRAGE_DESCRIPTION"
    Value "Bombards the area with ghostly energy, dealing damage to all objects within the blast radius." 
Ofc I added them in the alphabetical correct place. To finish I opened: CAPITALSHIP_PSIBATTLESHIP and changed this:
ability:0 "AbilityAntiMatterDetonate" => ability:0 "AbilityGhostBarrage"
 
To my knowledge this should have worked. However now my game minidumps on start up. As soon as I remove these changes, it all goes back to working as it should. What am I doing wrong?