1. Sign in to your Tumblr Dashboard. Click on your profile icon on the top right corner, followed by Edit appearance:
2. Click Edit theme:
Followed by Edit HTML:
3. Search for "<body>" in the HTML-code. You can now paste the HTML-code from Bloglovin (if you haven't gotten a widget code yet you can get it here) anywhere after body depending on where you wish to have your Bloglovin widget. Since all Tumblr themes are different this might look a bit different than the coding in other themes.
4. Paste the code where you want it. I pasted it after archive because I want the widget in that section.
5. Press Update Preview and the Bloglovin widget will show up (see below)
6. Click Save and you are done!