> For the complete documentation index, see [llms.txt](https://help.littledata.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.littledata.io/event-editor/getting-started.md).

# Getting started

This guide will help you build your first customization end-to-end: a custom event that gives your best-selling product its own conversion in Meta.

### What you'll build

A custom event based on **Purchase**, scoped with a trigger condition so it only fires when the order contains your best-selling product. Sent to Meta as its own event, it gives the algorithm a dedicated conversion to optimize toward, instead of lumping your winning product in with every other purchase.

### What you need

* Your best-selling product, and its exact title or SKU as it appears in Shopify
* [Meta Conversions API](/integrations/facebook-capi.md) connected as a Littledata destination
* Access to the Event Editor in the Littledata app

### Steps

{% stepper %}
{% step %}

#### Open Littledata

Open the Littledata app from your Shopify admin.
{% endstep %}

{% step %}

#### Open the Meta destination's Event Editor

Go to **Settings** for your Meta Conversions API destination, then open the **Event Editor**. This lists every event Littledata sends to Meta, standard and custom side by side.

<figure><img src="/files/ePA527wkPh4qyOge2n02" alt=""><figcaption></figcaption></figure>
{% endstep %}

{% step %}

#### Add a custom event

Click **Add event**.

Name the event after the product, for example `bestseller_purchase`.

Select **Purchase** as the base event. The custom event inherits the complete field mappings of its base, so it sends a full, valid payload from the start. See [Derive a new custom event](/event-editor/custom-events.md).

<figure><img src="/files/ZjNhLt0LzvfjOnzhWgVu" alt=""><figcaption></figcaption></figure>
{% endstep %}

{% step %}

#### Scope it to your product

Without a condition, the new event fires on every purchase. Add a trigger condition so it only fires when the order contains your best-selling product. Some possible options below:

<table><thead><tr><th width="214.75">Field</th><th>Operation</th><th>Value</th></tr></thead><tbody><tr><td><code>products.title</code></td><td><code>contains</code></td><td><code>&#x3C;your product name></code></td></tr><tr><td><code>products.collections</code></td><td><code>contains</code></td><td><code>skincare</code></td></tr><tr><td><code>products.category</code></td><td><code>does not equal</code></td><td><code>Health</code></td></tr><tr><td><code>products.product_type</code></td><td><code>does not equal</code></td><td><code>Health</code></td></tr><tr><td><code>products.handle</code></td><td><code>equals</code></td><td><code>product-handle</code></td></tr></tbody></table>

<figure><img src="/files/tSSnbxWoi4jdhC8tkj6D" alt=""><figcaption></figcaption></figure>

See [trigger conditions](/event-editor/trigger-conditions.md) for more info.
{% endstep %}

{% step %}

#### Preview and save

Use the event preview to check the payload, then click **Save**.
{% endstep %}

{% step %}

#### Mark it as a conversion in Meta

In Meta Events Manager, mark `bestseller_purchase` as a custom conversion. Then choose it, not the general Purchase event, as the optimization event for campaigns you want focused on that product, for example a launch push or a margin-protecting promotion.
{% endstep %}
{% endstepper %}

### Verifying it's working

1. Place a test order containing your best-selling product.
2. Confirm `BestsellerPurchase` arrives alongside the standard `Purchase` event in Meta **Events Manager**.
3. Orders without that product should fire `Purchase` only.

### Where to go from here

Aside from creating a [custom event](/event-editor/custom-events.md), you can also:

* [Enrich events with outside data](/event-editor/custom-data-sources.md): pull in values from Shopify metafields, like a loyalty tier or product attribute
* [Remap existing events](/event-editor/field-mappings.md): change what field a destination reads a value from
* [Enable or disable events](/event-editor/enable-disable-events.md): turn an event on or off per destination

For more worked examples, browse [Common setups](/event-editor/common-setups.md).