i think im lacking imagemagick on my server, what would the yum command be to install that as i have no clue?

yum install <package>.

I've not used phpBB. Is it derived from RedHat?

If so you can use "yum list installed" to see what commands are available. (Note later Fedora uses dnf rather than yum so if phpBB is derived from Fedora use dnf rather than yum.)

The package on RHEL/CentOS is "ImageMagick". Linux is case sensitive.

Running "yum list ImageMagick" would show any packages available in repository and any already installed.

"yum install ImageMagick" would install that package if found in the repository.

"yum update ImageMagick" would update to latest version from repository if you have older version installed.

If phpBB is not derived from RedHat it may no use RedHat Package Manager (RPM) which is what yum and dnf work with. There are other package managers for other distros. Those derived from Debian (including Ubuntu derivations) you'd use apt-get rather than yum.

there are TWO imagemagicks in the repos
Q8 and Q16 ( for the third Q32 you need to build it )

first do a yum search
then from that list install the one you need

You could also look at http://www.graphicsmagick.org/README.html, a derivative.
Available as a pkg in RHEL6.
If you can't find a pkg for your OS, see http://www.graphicsmagick.org/INSTALL-unix.html