Example - Railgun Efx from SG:WB
at universe/engine/efx.ini (or mod_efx, if you want original Nexus efx working with your mod too)
EFX 4 // Railgun
NoModColor /// Color will not be changed by race
STRIP
Texture 11 /// See manual about this
Length 6 ///Self-explanatory
Radius 12 ///Self-explanatory
Color 1 1 1 ///Red Blue Green colors
STRIP
SOUND
Index 207 208 /// From universe/engine/sounds.ini
Level .5 ///volume
SOUND
EFX
at universe/tactycstipes.ini
DEVICETYPE 5
Name "Railgun"
.
.
Start 2 0 3 0.1
Travel 2 800 4 7.2 ///Third number is the number of the effect (1st type, 2nd speed, 4th size)
End 1 1000 5 0.5
DEVICETYPE
I really recommend to go through efx part of modding manual again because efx part is quite well explained there.