Go to your Account Settings and click Edit Appearance. Then select Edit Theme.
Underneath Custom Theme, click Edit HTML.
Copy and Paste Script
Paste the POWr script into the HTML file between the Head tags. Update, then save.
New Text Post
Back inside the Tumblr editor, embed a new Text Element.
Copy and Paste Shortcode
Paste the POWr shortcode into the text post, then save Expand the post to see your new Image Slider plugin. Click the POWr Settings Icon to set up POWr Image Slider.
To edit your Image Slider on Tumblr:
Visit your live Tumblr website and click the Settings Icon in the upper right corner of the Image Slider Plugin.