Chromium? Yes I’m referring to the Chrome browser. But are you aware that the Chrome browser is a fork of the open source Chromium browser? G-Chrome just has some proprietary software from Google added in.
For most purposes I always use the words Chrome and Chromium interchangeably.
When editing a website you can proceed in various ways.
There are expensive tools to edit your site that you can purchase or you can just use Chromium and a text editor.
Generally, you will want to model your changes then commit them.
To start, right click (Ctrl+click on Mac) the context menu contains a link that should say “Inspect Element” or “Inspect”.
That gives you access to the developer tools. In some systems you can also access this by pressing f12.

Make sure to select the element that you are wanting info on in the left panel.
You can make changes to nodes in the left by selecting one and pressing the F2 key.
Changes can also be made here by editing the styles tabs or using the console to enter and test JavaScript.
The changes don’t take effect on refresh though .. unless you copy them into the editor of your website, but that’s a subject for another post. 😉
Good Luck!