The Lightning network is a layer-2 protocol to Bitcoin. The money being transferred is still bitcoin, but is sent via a payment channel, through which any amount of transactions can occur without incurring main chain fees for every back-and-forth.
In order to send and request payments for your web applications, you will need a working Lightning Node. This guide assumes LND since they have implemented Macaroons.
You can either: set up your own node or use a hosted solution like Voltage.
The easiest way get up and running is to use Nix:
nix-shell -p lnd bitcoin.
The repository for this module includes a shell.nix file with the minimum requirements to develop this application, and you can modify it to include lnd and bitcoin, and run them locally that way.
For platform-specific setup details, see:
The first time, you'll likely want to run the node in regtest mode.
Write down your seed words!
If you plan on hosting your own node, we recommend using nix-bitcoin's declarative configuration. It's easy because you can write the configuration once, change it in one place, and deploy it as many times as needed. A basic and thoroughly documented example lives here.
Using a hosted node makes sense if you don't think you'll be able to secure your node, or if you don't have the infrastructure to run a bitcoin + lightning node. Downside of Voltage and other hosted nodes is that you can only run mainnet nodes. It's often helpful to be able to test in a either simnet or regtest.