The canvases don't have an alignment command but the CanvasTextWidthFN function returns the width of the specified text. With this function and knowledge of the canvas width you could align your text. I'll let you have fun working it out for centering.
@ Right align for canvas 1
Local text,twidth,cwidth,xpos
Put CanvasWidthFN(1) into cwidth
Put 'Hello World' into text
Put CanvasTextWidthFN(1,text) into twidth
@ align right
Put cwidth into xpos
Subtract twidth from xpos
CanvasDrawText(1,text,20,xpos)
I haven't ran this code so there might be some typos.