A Forex trading plan is not very different from any other plan. It is an overview of your planned trading activities based on certain parameters you have chosen. It is similar to a checklist of tasks to be completed in trading activities.
The main idea of the trading plan is to develop a set of rules to follow and to know how to implement them. Once you have these rules written down, it is easier to apply them because there is a clear action plan for how you manage daily trading.