This article shows you the process for editing an existing Contact record in Salesforce.
Using Search to Find & Edit
To update a Contact record, search for the Contact via the Global Search and click on the Contact Name to access the record or click Edit to view the record in Edit mode.
If you haven't accessed the record in Edit mode, you can click the Edit Button on the Contact Detail Page or hover over a field and click on the Pencil Icon.
In edit mode all editable fields (not read only fields) will be visible and you can make updates as needed. Click Save to commit the updates to the database.