How to put objects or buildings on the GTA 3 map?

[Báradock DDMT]

Hello members, I know this question has already been answered a few times, but I have something special for you, I know it's not an ambitious project I have in mind but I like the idea of making mods.

I want to modify the map of a famous GTA 3 mod, the well-known GTA Frosted Winter, that mod where Salvatore's son is the protagonist of a revenge adventure some time after his father's death. I know that the mod adds new buildings and structures, this inspired me to know how to make my own structures to put in the game, for example putting a Christmas tree or adding already made buildings like Alcatraz or WTC.
I have tried to create them .ipl , .ide and .col but it tells me that there is an error when running the game and I don't know why this happens or what I'm doing wrong; it's worth mentioning that I have these programs:

notepad++
KED and MED
Magic TXD
CollEditor2
IMGTool
3ds Max
Blender
III.VC.SA.LimitAdjuster