diff --git a/CHANGELOG.md b/CHANGELOG.md
index aa4bf6b..527b0c4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changelog
 
 ## 2026-02-26
+- Added `WIKI.md` quick usage guide with setup, workbook workflow, key formats, validation, and push/mirror steps.
 - Simplified `Remediations` status options to `exception`, `exception - permanent`, in-progress variants, and `resolved`.
 - Added `Excepted until (date)` to `Remediations` and `Template`, with overdue-date highlighting (red) when the date has passed.
 - Added `First seen` to `Remediations` and `Unresolved for` to `Template` (`days` since first seen when first seen is before today).
diff --git a/README.md b/README.md
index 59b043c..7f7bb0d 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 This repo generates an `.xlsx` workbook for tracking Nessus remediation items.
 
+Quick operator guide: [WIKI.md](WIKI.md)
+
 ## Dependencies
 
 - Python `>=3.10`
diff --git a/WIKI.md b/WIKI.md
new file mode 100644
index 0000000..571ce0c
--- /dev/null
+++ b/WIKI.md
@@ -0,0 +1,37 @@
+# Nessus Tracker Quick Usage Wiki
+
+## Purpose
+Use this workbook to track remediation state for Nessus findings by matching `Template` entries to `Remediations`.
+
+## Core Workflow
+1. Update `Remediations` rows with latest findings/status.
+2. Set `First seen` when an item first appears.
+3. Set `Excepted until (date)` when status is `exception`.
+4. In `Template`, enter `Key` values to build a report view.
+5. Fill `Hosts` and `Owner` manually in `Template`.
+
+## Key Formats (Template column A)
+- `CVE:CVE-2025-61726`
+- `PID:505201`
+- Raw values:
+  - `CVE-2025-61726`
+  - `505201`
+
+Matching order:
+1. CVE match (trimmed text match, whitespace tolerant)
+2. Plugin ID match (numeric-first fallback)
+
+## Behavior Notes
+- `Key` blank => auto-populated cells stay blank.
+- `Key` unmatched => key-driven fields show `NEW ITEM` where applicable.
+- Auto-populated fields stay blank when source values are missing.
+- `Name` in `Template` links to the matched `Remediations` row.
+- `Unresolved for` shows days since `First seen` (when `First seen` is before today).
+- `Excepted until (date)` highlights red when past due.
+
+## Allowed Status Values
+- `exception`
+- `exception - permanent`
+- `In progress - next updates`
+- `In progress - researching`
+- `resolved`
\ No newline at end of file