When you are looking at the recipes listed on the left side of the Planner you will see the recipe name to the right of the photo. If you click on the recipe name you will get the recipe details.
To the right of the recipe name is a symbol called a "handle" (it looks like 4 arrows pointing in different directions). If you click and hold the handle you will be able to drag the recipe onto the planner and move it from one day to the next. Those of you on a tablet will need to click and hold on the handle, with some intention, so that your tablet recognizes that you are wanting to drag your recipe instead of scrolling the recipe list.