Trying to install a module that uses composer

[babyewok]

OK I have PS 1.6.1.1 and I came across this module https://github.com/firstred/mpsendtoafriend which apparently gets around the whole spam/ insecuruty issue of the native PS send to a friend module.

 

I tried to install it and got this:

 

[PrestaShop] Fatal error in module file :[..removed...]\modules\mpsendtoafriend\mpsendtoafriend.php:
require_once(): Failed opening required [..removed...]/modules/mpsendtoafriend/vendor/autoload.php' (include_path=[..removed...]\tools\htmlpurifier/standalone;.;[..removed...]/home/us_pear/PEAR')

 

I opened an issue on github and was told 'Use composer' and the issue was closed!  Not very heklpful!

 

How do I use composer to install a module on Pretsahsop?