My biggest question is how to implement this mambo jumbo, I was confused and couldn't asked anyone about this technically because most of friends don't use this or maybe they know about this but they let developer do the magic.

First, Which Ecommerce Reports Option Is Right for You?

If you want to see only sales data and how well each product performs, which traffic sources generate sales, then choose Standard Ecommerce functionality.
If you want to see not only purchases but visitor’s journey as well (data related to Add to cart activity, Checkout steps, etc.), then Enhanced Ecommerce should be your option.

I started to asked the user if you need only product sales or all from beginning to end. The choice was Enhanced Ecommerce so from there we begin.

It is much more difficult to implement Enhanced Ecommerce functionality, additionally, it requires much more developer’s time to get things going. Therefore, you’d need to weigh your options. With Enhanced Ecommerce, you’ll get much more insights, but it’s much more expensive to properly implement and also takes longer.

You'll need to enable Ecommerce Feature

You need to enable Ecommerce for each view in which you want to see the data.
Sign in to Google Analytics.
Click Admin, and navigate to the view you want.
In the VIEW column, click Ecommerce Settings.
Set Enable Ecommerce to ON.
Click Save.

How to set funnel after enabling Ecommerce

I somehow not using this in the end, I lack of understanding of this concept of funneling... but i made an example from the sites I made to get a grasp of funneling.

Example That I found

Shipping Detail
Payment option
Confirmation
Login
Delivery Address
Billing Information
Review Order
Place Order
Contoh Fotofilio

Login
Order
Confirmation Order
Show Order
Pick Image
Confirmation Payment
Example Muslimadani

Visitor
product
add to cart
signup
checkout
verify payment
Example Pintaria

Login
Product Detail
Place Order
Thank You

Should I use Data Layer Or Enhanced Ecommerce

I can't seem to grasp the concept of Data Layer, I thought that Data Layer and Enhanced Ecommerce was the same (Will continue on this when I get more knowledge of this).

The problem was in the site I was building there was already a tag manager tracker, I couldn't find any google analytics tracker, so I assumed the GA tracker is implemented using Gtag Manager. Then Another question pops to mind, so if we are using Gtag Manager should I use data layer? This concept got me confused ( still got no one to ask )

Data Layer : https://developers.google.com/tag-manager/enhanced-ecommerce
GA : https://developers.google.com/analytics/devguides/collection/analyticsjs/enhanced-ecommerce
Gtag : https://developers.google.com/analytics/devguides/collection/gtagjs/enhanced-ecommerce

The data layer link above uses Datalayer, GA, Gtag uses different kind of syntax where should you start tinkering?

For me the answer was, I followed the tag tracker code that I was using, for me was using gtag.

How would you know when your tag is working

For a quick view, you can go to real time > event

What to do when you have no basic of GA at all

Go to this website, register to this course

https://analytics.google.com/analytics/academy/

For me it was no use but I learned some basic stuff here