Can someone give me more specific answers than LadyCFII gave
on how to install a game mod ?
Highlight below:
I have a Windows DELL.

Ah, I can't; I've seen that thread, and the instructions there are very complete; I don't think I could do better.

What part of the instructions are giving you problems? Maybe if we can narrow it down abit, you can get more specific help with that step/area.

The ones on how to install a game mod

What part of those instructions confuses you? The thread I saw was pretty complete.

You've tried to follow these instructions, right? At what step did you start having trouble? It'd be helpful if you told us what you did at each step, and what happened on your computer.

For instance, in this format:

1: Make sure that VV3 is not running (quit the game, if it is)
Okay, I quit.
2: Open My Computer and navigate to the folder where VV3 is installed (usually c:\Program Files\Virtual Villagers - The Secret City)
I navigated here, found the folder in the right place.
3: Open the VV3 program folder
Oh noes! Windows exploded!

That's kind of fanciful, I admit, but this kind of step-by-step would help us figure out what's happening, even if something's going wrong in the process even before you realized something wasn't working right.