No problem i'll try to be more precise this time O0

Just in case i'll start from the begining.

First you need to download the mod tool, then after install it, go to raw/english/localizedstrings

This folder contains all file with localized content for the gam...

Hello,
If you're talking from stock singleplayer map, i can think of only one easy way:

Take the localizedstring file located in raw\english\localizedstrings of the mission you want to modify, in this there will be some INTROSCREEN_XXXX line, modify it.
Then in your mod.csv ...