Do EXACTLY what this guide tells you and it should work....
1.OK first you need to download WinRAR.
2.Then double click on the ResGestae-PrometheanLegions-Patch_5 file and double click on the Res Gestae file and there should be two files named "languages" and "data".
3. Before you start overwriting the files, go to MyComputer-->Local Disc (C)-->Program Files--> Activision--> Rome - Total War and double click on Rome total war.
4. In the top left corner there should be a file called "data." drag the file from the patch onto the data folder. If it says it is going to overwrite something (I can't remember if it does.) click on "Yes to All." So now you have finished the data part of the job. The languages folder still remains. NOTE: DO NOT CANCEL OUT OF THE RTW FOLDER YET.
5. Seeing that you speak English fluently, I guess that your native language is English.
6. Double click on the languages folder in the WinRAR file.
7. Select English from the list.
8. Then double click on text in the file.
9.Since you are still in the RTW folder, double click on data.
10. Then find the folder labeled "text" and double click on that.
11. Drag and drop the .txt files from the Res Gestae file and drop it in the folder. When it asks if you want to overwrite, say yes.
12. You should now be completed with that and you can now exit out of the folder.
The UI Patch
1. Double click on the Res Gestae UI patch.
2.Click "install" when it comes up. It will install, and it will open another "document" I guess you could call it.

3. You will have to wait a few minutes, since it has to unpack everything. After a while it will say "press any key to continue..." so like it says, press any key to continue.
4.Then it will install all these files into the RTW folder. It will have a series of times when it says a unit name and asks if you want to install it. Press and hold "y" for each one. Since you're holding "y" down, it will go by much faster.
5. Then you're going to have to repeat steps 3 and 4 and after that you should be done.
If you need any more help, don't bother to ask. I can provide pictures if needed.