Simple extension

[tzn1]

I would like to create a simple extension where I can put some simple javascript code that will run on page load.

How to create the folder structure for it?

I currently put my file here:
files/client/modules/mymodulename/lib/mylib.js

And configured here to load it up:
files/application/Espo/Modules/mymodulename/Resources/metadata/app/jsLibs.json

mylib.js contains only this just to test it out:

(function () {
alert("hello");
})();

And the jsLibs.json contains this:
{
"mymodulename": {
"path": "client/modules/mymodulename/lib/mylib.js",
"exportsTo": "$",
"exportsAs": "mymodulename"
}
}

It is not working. is there any way to make this work so the page will alert upon load?

TN