There are many different web browsers on the Internet. They do NOT all display pages the same way AND not all of them fully support newer tags and standards. It is important that you view your pages on tmultiple web browsers. The list of browsers shown below are the most popular. Windows users can download all but Safari.
1) Chrome https://www.google.com/chrome/browser/desktop/index.html
2) FireFox https://www.mozilla.org/en-US/firefox/
3) Opera http://www.opera.com/
4)
Microsoft Edge https://www.microsoft.com/en-us/windows/microsoft-edge
5) Safari https://support.apple.com/en-us/HT204416 (no longer supports Windows)
You can download all of them for free by going to the websites displayed
above.
The Can I Use... website indicates which features are supported by the
browsers listed above, in addition to mobile devices: http://caniuse.com/
Web Host - You do NOT need to worry about obtaining a host for your web pages. I have my own domain and I will be creating accounts for you. This will allow you to focus on learning html 5 and css 3 and it allows me to help you if problems arise because I can see your file/folder structure and have direct access to your code :)