add section explaining signals and how they relate to events

Author: pwseg

src/connections/auto-instrumentation/event-builder.md

@@ -1,4 +1,40 @@
 ---
 title: Auto-Instrumentation Event Builder
 hidden: true
----
+---
+
+The Event Builder provides a no-code way to define analytics events based on signals collected by Auto-Instrumentation. 
+
+You can use it to create Track, Identify, Page, and other event types directly from your Segment workspace.
+
+> info "Auto-Instrumentation Private Beta"
+> Auto-Instrumentation is currently in Private Beta and is governed by Segment's [First Access and Beta Preview Terms](https://www.twilio.com/en-us/legal/tos){:target="_blank"}. Segment is actively iterating on and improving the Auto-Instrumentation user experience.
+
+## Access the Event Builder
+
+The Event Builder appears as a tab within each source, next to the Debugger. If you don't see the Event Builder tab, first confirm that you've installed the required Auto-Instrumentation SDK. If you've installed the SDK but still don't see the Event Builder tab, reach out to your Segment account manager to verify your workspace is included in the Auto-Instrumentation Private Beta.
+
+> info "Event Builder during Private Beta"
+> During Private Beta beta, both the Event Builder and the legacy Auto-Instrumentation tab appear in the navigation. Segment will remove the legacy tab once all customers have migrated to the Event Builder experience.
+
+## Generate activity
+
+To see activity in the Event Builder, you need to trigger signals using a custom debug link that Segment provides:
+
+1. In the Event Builder, copy the custom URL shown at the top of the page.
+2. Open your website or app using that URL in a browser or mobile device.
+3. Try out some typical user actions (like clicking buttons, navigate screens, and triggering network calls).
+
+Segment collects and displays activity as signals. These signals are grouped into types, like:
+
+- Interaction: clicks, taps, and UI interactions.
+- Navigation: screen changes and page transitions
+- Network: requests and responses
+- `LocalData`, Instrumentation, and `UserDefined`: additional signal types from the SDK.
+
+### How signals relate to events
+
+Segment separates signal collection from event creation. Signals represent raw user interactions, like a button click or screen view. Events, on the other hand, are analytics calls you define based on those signals. This two-step process lets you observe user behavior first, and then decide how and when to turn that behavior into structured analytics events, without needing to modify your code.
+
+Signal detection is active for 24 hours after you generate activity. Detected signals are available in the Event Builder for 72 hours.
+