trying to get DBD::mysql to install on my centos server

CentOS 7 seems to have perl-DBD-MySQL-4.023-5.el7.x86_64.rpm package, so all you need to do is yum install perl-DBD-MySQL.

Also, try entering look DBD::mysql in CPAN shell and then perl Makefile.PL && make (in the regular one, which should open). This way you will see the full output of the make command, including the error.