Well, basically you have to write down the main goals of your lesson or number of lessons, writing something like this: At the end of this unit/lesson students must be able to and then you make a short list of the main objectives of your lesson, what you want your students to be able to do at the end of the "secuencia didáctica".
Then you have to decide which activities you are going to do so tha the goals are achieved.
These activities are going to be the steps: For example, if you want your students to know the alphabet at the end of an unit the first step could be something like this: Step 1: students listen to the Alphabet Song.
And you do this as you go along with your plan.
If you want, send me a PM and I will see if I can help you more specifically.
Or maybe you can type: lesson plans in the search engine here at eslprintables and see examples of lesson plans.
Georgina