If you have entrenchement v 1.041 then you place or unzip the mod to this folder:
C:\Users\[YOUR NAME HERE]\AppData\Local\Ironclad Games\Sins of a Solar Empire\Mods-Entrenchment v1.041
You can find this location by clicking on START ---->YOUR NAME---->APP DATA---->LOCAL----->IRONCLAD GAMES--->SINS OF A SOLAR EMPIRE---->MODS-ENTRENCHMENT V1.041
If you click START--->Your Name but, do not see the APP Data folder then you will have to click on ORGANIZE from the command bar----->FOLDER AND SEARCH OPTIONS---->the VIEW tab and then make sure that the round button for SHOW HIDDEN FILES AND FOLDERS is checked. If you do this you will then be able to see APP DATA.
Once you have the files in the correct folder you then run Sins and then go into options and simply enable the mod you wish to play. If this is the first time you've tried to install a mod you may have to run the game and enter the option---> mods and then exit the game and then run the game again and they then should show up. I hope this helps...