The document "D4.6 GREENGAGE experiment and monitoring system and manual" from the Horizon Europe project GREENGAGE focuses on innovative governance, environmental observations, and digital solutions supporting the Green Deal. This document's audience is any of the stakeholders that will be involved in a Thematic Co-Exploration and any person who aims to understand the Citizen Observatory Community Journey. It details citizen engagement in environmental monitoring through Citizen Observatories in European cities. The document outlines three areas of concern: Citizen Observatory Community Journey, including Community and Co-production Process Management, Data Crowdsourcing and Curation, and Analysis and Visualization for Insights Generation. It emphasizes the use of various digital tools and applications for data collection, analysis, and visualization, aiming to enhance city decision-making processes and governance with citizen participation and diverse data integration.Additionally, the document includes a comprehensive review of the usage statistics and impact assessment for each digital tool and application used in the GREENGAGE project. This analysis focuses on evaluating the effectiveness and reach of these tools in engaging citizens, enhancing data collection, and contributing to better environmental governance and decision-making processes in European cities. The assessment aims to measure the success of the project in terms of citizen engagement and the quality of data obtained through these innovative digital means. This document is a second iteration of deliverable D4.2. Changes from the previous version are clearly indicated.