First, unpack the .zip, and drag the contents into root/raw/fx so the fx get put in the right folders.
NOTE: the FX in the download are called raygun_ug_ug as Im using them for double pap, for the sake of this tutorial, keep the names the same or you will run into trouble with the ring_emit fx.
Then, Open your Ray Gun's weapon file (PAP or non PAP, doesn't matter) I recommend UGX weapon editor, makes it a whole lot simpler.
Then change these settings:
Sorry but you are not allowed to view spoiler contents.In most cases, it simply involves adding _ug_ug to the fx name.
And you are done! Rebuild your mod and it should work!
TO CHANGE COLOUR:
Open Effects editor from launcher and open the FX from the download
Make sure to select each part of the fx before using the graph on the right to change colour, by sliding the lines around (It is a little difficult to do colour like this, but play around with it and it becomes easier)
You can change the colour so it starts of one colour and fades into another also:
That's it! The FX are simply the copied original ray gun ones set up for easy editing.
If you use this, Please credit me and HitmanVere, as he helped me get the ring_emit fx sorted
EDIT: Knew I'd forgot something, make sure to add this to your mod.csv before rebuilding it: