One of the benefits of using WordPress is that it allows you to edit your images from within the post itself, rather than having to edit it through another application or some other means. This allows for convenient post and page management, and work simplicity.
To start editing your image, simply click on it. Doing so will bring up points around the image itself, which you can click and drag in order to scale the image as you wish. When you click on the image, you will also see the alignment tools for them – clicking on those will allow you to, of course, align the image how you would like within the post, as well as preview how the aligned image will appear among the post itself.
For further options, click on the edit icon, which will allow you to set the caption, the alternate text, manually specify image size, and give the image a clickable link.
You can also use the advanced option to define custom CSS or Rel attributes.
If you need further control when editing your images, you can use the Image Editor located in the image library.