The blocks under events pane are called as Hatblocks which can only be connected below. This blocks are called as hatblocks as they have hat like top side where you can't connect anything. For example the Start green flag block,

Coming to the problem discussed above to draw a square with single click,

The solution is to set a variable four and make it repeat.

To create a variable go to the variable tab in the blocks pane on the left side and drag the set and my variable. Drag the myvariable to repeat block and do the steps that you have already done in square exercise

Exercise:

Draw three squares with help of two variables.

Draw three squares but with gap of 100 steps with each other

Solution: