Edit Appearance Edit Theme
In your Tumblr dashboard, open your Account Settings. Select Edit Appearance and click Edit Theme.
Go to Edit HTML.
Paste the Script
Paste this script into the Tumblr HTML file. It's always best to paste it between the Head tags. Update, then save.
Create a new Text post in the Tumblr dashboard.
Paste this shortcode into the post. Expand the post to see your new Slideshow plugin. You can edit POWr Slideshow by clicking the POWr Settings Icon in the corner.
Start to customize your Slideshow Plugin:
Visit your live Tumblr web page and select the gear icon in the top right corner of the Slideshow Plugin.