The answer to 'how to fix pipe' is to first identify the type of pipe and the issue. For a simple leak or clog, you may be able to fix it yourself with a few basic tools. Start by turning off the water supply to that pipe, then inspect the pipe to find the exact location of the problem. Use a pipe wrench or pliers to tighten any loose fittings or connections. If there is a crack or hole, you can try applying a pipe repair clamp or epoxy sealant to stop the leak. For more complex issues like a burst pipe, you'll likely need to replace the damaged section.
If you're not comfortable doing the repairs yourself or the problem is severe, it's best to call a professional plumber. They have the expertise and tools to properly diagnose and fix the issue, ensuring the repair is done safely and effectively.