Glad you liked the article.
The only muscle group you are after is the pectoralis. There is a major and minor to this, but any chest exercise you can do for one will attack the other.
Whether you have pecs that attach to your sternum near the middle of your chest is what determines how they look.

The good news is that you can structure your chest routing so that you are emphasizing the upper chest or the lower chest.
This is because a routine that emphasizes the upper chest will also hit your anterior deltoids and all the small supporting muscle groups that assist with lifting in that direction. Here’s a simple workout for upper chest:

Incline bench presses
Incline dumbbell flys
Pushups with feet raised

Here is what a routine for lower chest would look like:

Flat bench presses
Dumbbell Flys
Decline Presses

You could also throw dips in there, to give your triceps something to keep them from becoming bored.
Hope this helps!