How do I construct my ideas into an essay

Your essay should consist of your introcudcion, body, and conclusions. Your introduction should state your argument/point of your paper, also known as your thesis, and should also tell the reader how they can expect you to support your claim. Many people get hung up on how to create a thesis statement, but all it is is a sentence or two stating what your paper is going to be about. If you were to tell your friend or parent what you're writing your paper on in a sentence, what would you say? From there, you can find your thesis statement and shape it into more academic language. For example, 'As we examine Mary Shelley's novel, Frankenstein, I will show that Dr. Frankenstein was not the monster, but that it was his creation.' 
The general set up for each argument section, or piece of evidence you provide, is to introduce your point, provide more detail, then connect it to your thesis, which is called sign-posting. Sign-posting is important as it reminds the reader what it is you're trying to prove, and also helps you to keep your arguments relevant. When providing more detail of your evidence, you can simply explain what you mean by the argument you're putting forward, add analysis from critics, or show arguments against it (though if you do this, be sure to show how you interpret the argument, agreeing or disagreeing, and if you disagree, state the relevance of its acknowlegement).
The conclusion should be reminding the reader of what they've just read, and why it matters. While you've provided each piece of evidence and showed that it relates to your thesis, now is the time to explain why these sets of arguments build together to make a strong argument altogether of your paper. If, for example, your thesis is 'this image is a duck', and your first argument is, 'it has feathers, ducks have feathers, so it's a duck', then, 'it has a beak, and ducks have beaks, so it's a duck,' and thirdly 'it quacks, and ducks quack, so it's a duck,' your conclusion should be that 'it has the physical characteristics of a duck, such as feathers and a beak, and also quacks. These things combined equate to the conclusion of the image being a duck.' This shows that the evidence combined only leads to one conclusion, which is your conclusion.