I know someone is going to ask this, so I’d better add: No, you can’t put text on both the top and bottom of a single circle - at least, not without severe and painful workarounds.

Choose Center from the Align pop-up menu, and Center from the To Path popup menu.

After you put the text along the top, choose Type > Type on a Path > Options.

Now when you center the text, it will center along the bottom, but it’ll be upside down.

Click on the top of the frame (12 o’clock) instead of the bottom.

What if you want to put the text along the bottom of the circle instead of the top?

Change the paragraph alignment to centered, start typing, and voilà, it appears centered.

This should put the text inside the circle. Now, with the circle selected, go to the Path menu, and select Reverse. The text will go to the outside of the circle (and you can rotate the circle until its at the top).

Click an insertion point directly on the bottom handle (at the 6 o’clock mark, as it were). Put your text on the circle as youve mentioned above.

Select the frame with the Selection tool so you can see its bounding box handles, and then switch to the Type on a Path tool (press Shift-T).

Make a circular frame with one of the Ellipse frame tools.

One of the more common effects people need to create is also one of the least obvious to accomplish: Centering text along the top of a circle or ellipse.

Inkscape curved text