Adding curved text is easy:

1. Click the Text tab from the side panel menu. 
2. Click Add curved text.
3. Once the curved text has been added you can customize the text using the text input box, the radius, spacing, reverse and RTL (right to left). 
4. You can customize the colour of this curved text and font like usual. 
5. You can also rotate this text element on the canvas. 

Definitions:

Curved Text: Curved text 

Radius: The arc/curvature of the curved text. 

Spacing: The spacing of the text. 

Reverse: Reverses the curved text. 

RTL: Changes the text to Right To Left.