How to add text along a curve in Paint by Zaweba
Put text on a curved path or shape edge with the Text tool in Paint by Zaweba, or bend it with Warp Text, and it stays editable either way.

Curved text is a click away in Paint by Zaweba. Select a path or a shape, then click on its edge with the Text tool and type, and the words follow the line; drag the start and end handles to set where the text sits. For a quick bend without drawing a path, use Type > Warp Text instead. Both ways the text stays editable, so you can fix a typo or change the font afterwards.
These two methods give different looks. Text on a path keeps each letter upright to the line, like lettering round a badge. Warp Text bends the whole block of text, letters and all, like printing on a flag or a balloon.
Text on a path, step by step
Draw the curve first. A circle from the Shape tool works for round badges and stamps, and the Pen tool gives you any curve you like, such as a gentle wave under a headline. With the path or shape selected, pick the Text tool and hover over the edge until the pointer changes, then click and type.
Two handles mark where the text starts and ends. Drag them to slide the text round the curve or to shorten the run. If the letters are on the wrong side of the line, or upside down along the bottom of a circle, use Flip Text on Path. A common badge layout puts one line of text over the top of a circle and a second, flipped, line along the bottom, both on their own paths.
Spacing matters more on a curve than on a straight line. Letters on the outside of a tight curve spread apart and those on the inside bunch up, so adjust the tracking until it looks even, and choose a slightly larger circle if the text looks cramped.
Warp Text for a quicker bend
Type > Warp Text bends text you've already set. The styles are arc, arc lower, arc upper, arch, bulge, shell, shell lower, shell upper, flag, wave, fish, rise, fisheye, inflate, squeeze and twist. Arc and arch suit headlines on posters; flag and wave give movement; bulge and inflate push the middle letters outwards for a cartoon feel. The text is still live, so you can edit the words and the warp follows.
Use warp sparingly on body text. Strong bends make small text hard to read. It's at its best on a short, bold word or two.
When you need the letters as shapes
Sometimes you'll want to treat the text as artwork, perhaps to edit individual letter outlines or to send it to a cutter or printer that needs vector shapes. Convert to Shape turns the text into a shape layer, and Create Work Path makes a path from it. Do that on a copy of the layer and keep the original text hidden underneath, because once converted the words can't be edited as text any more.
If you're exporting to SVG, text goes out as outlines anyway, so the look is kept without needing the font on the other computer.
Mistakes to avoid
Don't build curved text by rotating single letters one by one. It's slow, and the moment you change a word you have to start again. Don't rasterise text early just to apply an effect either; Layer Art effects such as strokes and shadows work on live text.
Paint by Zaweba is free software for Windows that works offline, and curved text is part of the same Type tools you use for everything else.