Hello there if you wanna know how to mod Grand Theft Auto V Story Mode this is the guide for you! I hope this helps!

1. You must have a legal copy of Grand Theft Auto V if you have the cracked version sorry i cant help you with that
2. Install OpenIV this will make it possible to mod your Grand Theft Auto game if you dont know the link here it is https://openiv.com/
3. Make sure you make a folder called Mods in your Game files which you can get there by right clicking on Gta then click on properties then click local files then press browse local files
4. After you have installed installed OpenIV you will see the files of your Grand Theft Auto
5. Now go onto https://www.gta5-mods.com/ and pick the ones you want and download them
6. Follow the instructions that the mod creator has given in the download
And there you have it you have modded your Grand Theft Auto V i hope it helped you out!