How to display text in pygame?

You can create a surface with text on it. For this take a look at this short example:

pygame.font.init() # you have to call this at the start, 
                   # if you want to use this module.
myfont = pygame.font.SysFont('Comic Sans MS', 30)

This creates a new object on which you can call the render method.

textsurface = myfont.render('Some Text', False, (0, 0, 0))

This creates a new surface with text already drawn onto it. At the end you can just blit the text surface onto your main screen.

screen.blit(textsurface,(0,0))

Bear in mind, that everytime the text changes, you have to recreate the surface again, to see the new text.