There are many Linux distributions that all work slightly differently and have different purposes. This can be complicated. Here is a list to help you get going.
This is my recommendation for everyone who has never used a Linux system before. It's easy to install, has lots of software available, and is relatively light weight.
Linux Mint is similar to Ubuntu Mate in many ways. The only issue is there is a few different editions to chose. Any Linux Mint edition will be great.
Elementary has been designed to be a system to convert people away from Mac and Windows. There's a large focus on a clean consistent design and they wrote a large amount of there own software to archive this.
Solus is a cool distribution for any type of user. Its the only one I have recommended for beginners that not based on Ubuntu. Its also special in the sense that its rolling release. This mean that once you install it you will never have a big version update again. You will just install updates to your software when ready.
In this list the first three distributions are based on Ubuntu. Ubuntu has been the biggest system of Linux for many years now. Its what I started with. Its still a good choice. I just feel that the ones in this list are just go a little step tougher in user friendliness. Check out Ubuntu here.
Installing Linux is different for every distribution. This is not a guide to installing but some suggestions to test things out.
To install Linux its not much different to installing Windows. If you have never installed an Operating system before you need to do a little research. If you are installing on a computer with all your files on you need to do a full backup first. Depending on choices you make when you install you could wipe everything on your computer.
If you want to test out some different Linux distributions one tool you can use is Virtual Box. This allows you to run a system on top of your existing system having to shrink or remove what you already have. It will be slower but its a good way to learn how things work before trying it for real. Do some research and try this out.
Another option is to get a cheap second hand machine to test with. This is the best way to get going as you can start by installing and trying a few different distributions and once you have something you like you can just use it. Old Lenovo ThinkPads are a good, plentiful, cheap option. Just have a look on EBay. Then you have no risk of ruining your main machine. Once you feel you know what your doing maybe you can move over to your main computer.