How to texture 3d objects for beginners

Here I will try to explain how to texture 3d objects to absolute beginners.
I'm not a beginner, I have over 10 years experience with 3d graphics so I may use uncommon words that for me are self explaining but in reality they might seem unclear. So if you have questions please ask them in the comments I will try to respond to them.

Lets start:
Before you apply your textures to an object, you have to apply a UV mapping to it.
How to create the texture itself I will show in another blog . Here you can find free textures and photos to start your 3d texture.

What is UV mapping?
Well UV mapping is a way to tell the computer what part of the texture will be shown on what polygon. This process is also called unwrapping the 3d object.
It is possible to apply multiple UV maps to an object one for every texture.
This is useful for many different situations that I will discuss later.
After you have added a UV map you have to apply the material or shader to your object. Different 3d programs do it in different ways so I will not concentrate on details. I will rather discuss the principles that will allow you to work with any 3d program commercial or not.
In short some programs allow to drag and drop the material to your object, or apply it through a menu where you click to assign material to selected objects. There can be a situation when you have to click on assign materials button then select the object to which it will be applied.

Now if you applied the material correctly your object should be the same color as your material.
If it is not try switching the modes of your viewport to show textures. Or try to apply the material again.