HTML Block

Can some one please explain in laymans terms how to use the HTML block in page builder.

So I added a html block to one of my existing pages, then changed the caption language key, then went to language settings and looked for the lang key I entered in the block and cannot find it.

So what did i do wrong?

Whatever you added as the caption lang key in block, you have to add in admin-->settings-->language settings-->add key

example:

caption lang (in block)-  _MyNewBlock

admin-->settings-->language settings-->add key  ||  Key Name--> _MyNewBlock

string text-    My  New  Block

[EDIT] - Topic Moved

 What do i do for Category when I Add Key, leave it on System or do i select the module I am adding the block to?

You could select the module you are adding to,  I use System 95% of the time.

OK, so if it is system, it will be available on all pages, and if it is for that particular mod then it will only be visible and available for that mod? Is this correct understanding?

In theory Yes, but setting it to a specific module if you use the same block lang name, then it will be the same string title on other modules.