The planning phase is really just getting the major people together that will own part of the project work and planning how they will do it and what they will need to get it done. In the business world, these are the Subject Matter Experts. A project manager does not need to be an expert in everything, but the project manager does need to find those that are and get those Subject Matter Experts on their team. This phase is also where you assign starting dates and ending dates to particular tasks. This is crucial to the projects success. There will be tasks that can happen at the same time that may or may not be related. But, some of those tasks will end later than others because they will simply take longer to complete. Start and stop dates also give you a way of ensuring that everything gets completed on time. This makes sense because the project has a specific stop date (otherwise it is a process), so all tasks have to end sometime. A word of caution, you are still in the "planning" phase here. Do not get overwhelmed with the lack of details. Every home needs a frame before it can be built. But, before the frame is constructed there is a rough idea of the total square footage of the home, how many rooms, bathrooms, etc. that there will be. Thats what the planning phase if for...to determine how this thing should look.