Simply follow the instructions below.
Click here to download manifest.xml and save it somewhere permanent (e.g. Documents\tech-bash).
In the ribbon, go to Insert → My Add-ins → Manage My Add-ins → Upload My Add-in.
Browse to the file you saved in step 1 and click Upload.
A tech+bash button will appear in the ribbon. Click it to open the add-in panel.
Go to office.com and open any workbook.
In the ribbon, click Insert → Add-ins → Upload My Add-in.
Download manifest.xml and upload it in the dialog.
Click the tech+bash button that appears in the ribbon to launch the panel.