In the given situation, which one of the instructions is correct?Having pressed the blue button, you have to enter the code, and then press the red button.

Writing instructions can help someone carry out a task they are not familiar with, or have never done before. The best way to write instructions is by using the imperative mood: this just means that you use the dictionary form of the verb to give an instruction, e.g. 'Stir slowly for two minutes'.