Go to ‘Media’, then ‘Add New’. Click on ‘Select Files’.
2.2 Information fields
Complete the information fields for the image.
This field will auto-populate with the name of the image file. So if your file is named “kitten.jpg”, by default this field will display “kitten”.
The WordPress caption provides detail and context to the viewer about the image, and is often displayed beneath the image – this is determined by your WordPress theme. As far as search engines goes, words in the caption count as if having them as part of the main text of the page. Note that you will find it easier to position images on your web pages if you leave the caption blank when uploading the image and add them later when finalising the page.
Alt text stands for “Alternative text”. It is not normally displayed on screen, but it will display for viewers who have images turned off or who are using screen readers for accessibility. Alt text is also significant in enabling search engines to index your images.
The description appears as the main text on the image’s attachment page, which is automatically created for each image you upload to WordPress.