If you go to the linked URL (https://beletronics.wordpress.com/learn-basic-electronics), and then click "Learn basic electronics – click to read", the table of contents shows "The building blocks" as step 1. The complete contents of this section are:
The building blocks
Simplicity is the ultimate sophistication.
(Leonardo da Vinci)
Hmm did you miss the introductory chapter that starts with diodes, transistors and basic logic gates that they told you vaguely about in high school physics?
There's quite a bit of info before getting to using the TTL chips.
Having played a bit with redstone circuits in Minecraft helps too - or knowing about diodes and transistors when doing redstone in Minecraft helps :)