I was trying to add a new unit for the first time. I Have PTW and the 1.12 patch. I got the correct graphic and filled in all the info. Now, when i went to save the edit as civ3x i got an error saying "ERROR: C:\Program Files\Infogrames Interactive\Civilization III\CIV3PTW\civ3X.bix is read-only and cannot be saved."

What have i done wrong and/or what do i do?

can i plz get some help on this issue...

You tried to overwrite the original Civ3 PTW bix file. Simply save your mod under another name than "civ3x.bix", and load then your new file in the game.

wut u mean load it into the game. doesnt it have to be under the "civ3x.bix" for it to work? Should i simply name the file "newunits.bix" or something?

Yep, use a different name, save it under Civ3\CIV3PTW\Scenarios\"yourfilename.bix" , then select "load scenario" in Civ3. Then you get a list of all bix.files in the "Scenarios" folder, simply load yours :)