You can use fancyhdr
.
With the option of the command \fancyfoot
you can control the positioning of the page number in the footer
L
on the left
R
on the right
C
in the center
As the argument of the command you can simply give \thepage
.
This results in
\fancyfoot[C]{\thepage}
You can also achieve something something more elaborated.
For example, using the package lastpage
you can print something like page 1 of 5, by defining the footer in the following way:
\fancyfoot[C]{\thepage{} of \pageref{LastPage}}
Or (something that I do), you can print in the footer the consent to the personal data processing (when needed).
In the following MWE you can chose between the two
\documentclass[11pt,a4paper,sans]{moderncv}
\moderncvstyle{classic}
\usepackage{lastpage}
\usepackage{fancyhdr}
\pagestyle{fancy}
% \fancyfoot[C]{\thepage} % only page number
\fancyfoot[C]{\thepage{} of \pageref{LastPage}}
\name{John}{Doe}
\begin{document}
\maketitle
\end{document}
Page number only:

Page 1 of n:

graphicx
and\graphicspath
are not relevant with respect to your question, while -for successful compilation-\name{}{}
is required.