canon 80d guided display, How do i switch from Standard to Guided

You would be looking for a display menu.

Want the bad news? Guided display is only on newer entry level models such as 200D, 800D and 77D.
Your attached image is not an 80d, the dial gives it away.

 

I would urge you not to bother selling and downgrading, your 80d is a much better camera to be honest. You will take a loss and then want to upgrade in the next year probably anyway. While the menus will walk you through doing things, you will still have to learn aperture priority for example the normal way eventually.

Using the example of Av mode - Takes the aperture you set and gives you the correct shutter automatically. That all it does, you don't need a picture menu. You pick how much of the background is in focus with the aperture.

We can surely help you with some of the basics on the forum. Most of us learned on a film camera without auto anything or display. (Mine was this) Still the best way to learn if you ask me.

 

Your setup looks pretty good to start. Building our kit takes time and knowing what you want out of the lenses.

The sigma lens - I don't have experience but from what I have ready its a pretty decent sharp lens in the center but will get soft in the corners especially when wide open (2.8 end of the aperture ring). This was a good option to recommend for the budget if you want to shoot wide angle shots such as landscapes or groups of people. This lens will only work on crop sensor bodies hence sigma using DC in the name. Sigma and Tamron make some good value choices for third party lenses if your looking to save some money.

The Canon 1.4 50mm - This is a great value priced prime, significantly better build quality over the plastic 1.8 version, not nearly as expensive as the 1.2 L lens they also make. Great news here is if you ever jump up to full frame you will still be able to use this lens. It was a good option to recommend if you at all want to shoot portraits.

Cost of lenses - You will either pay for speed or sharpness, mostly you will pay for both. You get what you pay for here, and it applies to zooms and primes. You will notice a prime lens like your 50mm will outperform a zoom lens at 50mm if you pixel peep on your computer. You also notice that the prime is wider at 1.4 than the zoom will ever go.

 

As far as learning how to use the camera, you have 3 things to learn how to tweak in manual mode to get started ISO, shutter, and aperture. Assuming you have the exposure dialed in right, those counter balance each other. So if you need to adjust the shutter faster to freeze action for example then you need give the shot more light somewhere else widen up the lens aperture and lessen depth of field or increase the ISO and add some digital noise(or film grain). That's exposure in a nutshell really.

Hopefully that will help drive some more targeted learning for you and don't be afraid to ask questions. I would encourage you to get familiar with the metering in the viewfinder and where you change each of those settings and then set it to manual and go. The only reason to use any auto modes is so you make getting a shot instantaneous if your in a hurry.

Do you listen to podcasts? I listen to one called the "Two Hosers Photo Show" its entertaining but it started as a guy showing his buddy how to use a camera so the first episodes are ISO, Shutter, etc.. and may be a good teaching tool for you. Then you can graduate up to more advanced stuff after the basics are covered.

 

No specific YouTube recommendations but watching ones on the subjects above listed will be a great idea, learn the exposure triangle i mentioned and you will be set.
Oh and honestly set it to manual and dial in the settings till the exposure is right. You will learn to work fast that way and not start relying on auto.