Add Single Media Items (Uploading Images)
First, open a post or a page to which you would like to add your media.
Click your cursor on the area of the post or page where you would like the media to show.
Next, click the Add Media button in the top left corner of your toolbar:
And click Add New to upload new media to your website.
You can also select Add via URL if your image is displayed elsewhere on the Internet, and you want to link it over instead of uploading it from your computer.
Create a Gallery/Slideshow
To create a gallery, upload multiple images and then select all of the images you want in the gallery at once:
Once you select all the images you want in your gallery, click Continue. On the next page, you can select the format you want for your gallery from the Layout dropdown options. If you want to create a slideshow instead of a gallery, click Slideshow from this list.
Click Insert when you’re ready to add the gallery/slideshow to your post or page.