Image in 3D World.

[Dreft]

How to create image in 3D World, for example on building wall or something like that ?

[50p]

You create object with replaced texture. Usually these are gang spray tags or billboards.

[Dreft]

Ok, then how to create dff and txd files with that picture I want to replace with model ?

[`Dmz]

Use G-TXD for editing GTA's textures.

[50p]

Ok, then how to create dff and txd files with that picture I want to replace with model ?

You don't need .dffs. They are models. You want to replace a texture of an existing model (which is a spray tag or billboard). Unless you want to make your own model.

You need to learn a little about modding GTA before you start making your own content for MTA.

And this is the place you are after:

http://www.gtaforums.com/

TXD Workshop or G-TXD are the main programs for making texture files for GTA.