I am pretty new to Linux as well and know how overwhelming it can be to try to Google for answers, so I'll show you what I have done, and maybe it will save you a few minutes of your life

.
From Dungog.net (
http://www.dungog.net/sme/repo.php):
From the command line enter the following, (or copy and paste into your ssh client)- If you are using Windows, downlad and install putty as your ssh client.
db yum_repositories set dungog repository \
BaseURL http://sme.dungog.net/packages/smeserver/7.0/i386/dungog/ \
EnableGroups yes \
GPGCheck no \
Name 'SME Server 7 - dungog' \
Visible yes \
status enabled
/sbin/e-smith/expand-template /etc/yum.conf
Install Update System from Dungog (
http://www.dungog.net/sme/admin.php#update)
yum install smeserver-updates
signal-event post-upgrade
signal-event reboot
Then download the rpm for
phpMyAdmin to your client machine. Go to SME's server-manager page and find the update system menu option (server-manager > administration > Update system). Browse to the rpm you just downloaded and click update.
I know that experience Linux users like the command line, but I myself have a hard time remembering the proper syntax; not to mention the enormous package names...
Hope this helps,
Ryan
Edit - I noticed that there is also a multi-user version of phpMyAdmin in the contribs, but I have not used it.