font size

[Baloff]

Hello
I am trying to change the font size.
after reading in info info on how to seach the info. I was able to
find in info emacs ps-font-size should do it.

but when I type ps<tab> in the mini buffer I get

Possible completions are:
ps-despool                         ps-line-lengths
ps-mode                            ps-nb-pages-buffer
ps-nb-pages-region                 ps-print-buffer
ps-print-buffer-with-faces         ps-print-customize
ps-print-region                    ps-print-region-with-faces
ps-spool-buffer                    ps-spool-buffer-with-faces
ps-spool-region                    ps-spool-region-with-faces

nothing about font size. 

help please

thanks