perl error: Can't locate LWP/UserAgent.pm in @INC

need to install libwww-perl

1, download package from cpan:
wget http://www.cpan.org/modules/by-module/LWP/libwww-perl-5.837.tar.gz

2, unzip it
tar xvzf libwww-perl-5.837.tar.gz

3, install pkg
cd libwww-perl-5.837
perl Makefile.PL
make
make install