If you have not already signed up for Sumo, check out the Getting Started with BDOW (formerly Sumo) Guide before following the instructions below.
Installing BDOW! on Tumblr
Log into your Tumblr Dashboard: https://www.tumblr.com/dashboard. Then click the Person Icon in the top Right. Then click Edit Appearance
Click Edit Theme
Click Edit HTML
Paste BDOW! code into head tag. (NOTE: Be sure to delete async="async" at the end of the BDOW! code you just pasted in.) and click on Save Template.
Congrats, you're all done! Now go to your Tumblr site and click on the BDOW! badge located in the top right corner to login.
Tumblr Mobile
Log into your Tumblr Dashboard: https://www.tumblr.com/dashboard. Then click the Person Icon in the top Right. Then click Edit Appearance.
Click Edit Theme.
Scroll all the way down the menu to the left and click Advanced Options.
Disable Use default mobile theme.