How do i add a script to a spell?

Newish to nearinfinity: trying to alter a script that buffs long lasting spells:

Hi, i have a script that buffs protection from fire etc on the party.

My qu is, i have a mod added spell spd.602 or something (cleric protection from cold).

In NI if i copy the script for protection from fire i can change the green text spw.xx to the new spd.xxx ir whatever and description, but the red text is looking for the spell from 'ids'.

If i open eekeeper i can see the new spell prot from cold has no 'script description' like protection from fire.

I have tried adding a line the to ids file but it seems i am missing something.

I basically want to have this new spell (in the override folder) used in the script.

Any help is apreiciated!

Thanks