To use a risk matrix, you must first identify the hazards that could affect your project, organization, or environment. You can utilize various methods, such as brainstorming, checklists, inspections, audits, or incident reports, to collect and document the hazards. Then you need to assess the likelihood and severity of each hazard - you can use quantitative or qualitative methods to estimate how often and how badly each hazard could occur. After that, plot the hazards on the risk matrix - you can use a template or create your own matrix using a spreadsheet or software. Assign each hazard a color code based on its likelihood and severity level. Finally, prioritize and manage the hazards - focus on the ones with the highest risk level (e.g., red or orange) and take appropriate measures to eliminate, reduce, or control them. Monitor and review the hazards regularly and update the matrix as needed.