WordPress has its own simple built-in Image Gallery that allows you to add multiple images to a page in one easy step.
To insert an image gallery into your Page/Post, click the Add Media button (). A pop-up window will display that looks the same as the one that displays when you add an image to your Page/Post. You can upload new images to use in your gallery or you can simply choose from your previously uploaded images.
By default, you’ll be shown a list of your previously uploaded images. If you’d like to upload a new image, click on the UploadFiles link at the top of the pop-up window.
Click the Create Gallery link in the left-hand navigation then select the images that you’d like to insert into your gallery.