I was afraid you were going to tell me that. Guess what? BINGO! You hit the jackpot. You had indicated that you own the following devices: iMac, iPhone, and iPad, is this correct? If yes, then read on and I will assume you are brand new to Apple, which is okay as everyone has to start somewhere. If you're not new to Apple, somewhere you have been mislead.
Where you noticed System Preferences/icloud/account etc.....that is what I was referring to. Once you get into "System Preferences," you might as well press every single icon there is on that screen and get to know those features like the back of your hand. This is basically your "settings" and this is where you will set up everything such as your email, security, firewall, printers, etc....everything!
You use www.icloud.com when you don't have access to any of your devices or you're using a Microsoft/Google computer and you want to check your email for example. Your desktop has all this so there is no need to visit www.icloud.com if you're using your MacBook or iMac or iPad.
Which leads me to my next question: I was wondering why you were using Safari, Chrome, and Firefox. Safari is Apple, Chrome is Google, and FireFox is Linux. I have no idea why you would be using all three? I think many others would say the same thing. If you are using these browsers for example to print something to your printer you have hooked up to your iMac, then we need to get you trained. It took me 2 months to understand Apple and within 6 months I became good at knowing where everything is and how to use. I'm excited for you to learn the power of Apple.
I don't know what iMac you have so I'm providing a link to help you at least explore your computer: Apple - Support - Manuals
Here are some manuals you may want to start exploring. Also, you can go to iBooks which is an app from Apple where you'll find many manuals and it's all free provided by Apple. You could buy a "Romance" novel too, but you'll have to pay for that. If you want learn how to program or become a developer, then you can get all the books from Apple for free. You haven't felt the power of Apple yet......you might as well buckle up and enjoy the ride! Apple will run circles around Microsoft and Google! Don't get me wrong, Microsoft and Google are great companies and have great products, but its like with Apple you're driving a BMW or Mercedes and with Microsoft you're driving a old, beat up car.
First, you need to set up your computer. This is so important and you'll want to protect your computer A.S.A.P. I'm confused though....How did you buy Apple products and not have the people show you or set it up for you? I'm curious because Apple people are awesome and they will take the time to show you various things and set your computer up so when you walk out the door, you're ready to get rolling with the basics.
Print this out: https://training.apple.com/content/dam/appletraining/us/en/2018/documents/macOS_ Support_Essentials_10.13_Exam_Preparatio…
Go to Amazon and purchase this book as I mention in a previous post. This link goes with the book, but it provides questions and answers to get you started. Also, check out www.macmost.com.
Go to www.youtube.com and check out various tutorials for free. Make sure you look up "Apple Operating System High Sierra 10.13." This is where you need to start. You need to get your iMac set up properly and more importantly secure. Your operating system is what runs the computer. Once you feel comfortable with the operating system, then explore the apps and what Apple offers. It's like building a house. You have to start at the foundation and have a strong foundation so your house doesn't collapse, right? If you explore the others areas first other than the operating system, then its like you're starting to build your home by starting with the roof. See my point? Who begins building a house with the roof first? If someone did, they are absolutely on drugs!