Hello - I'm wondering how could I update my php and mysql installations from within plesk?

We used to run Plesk 7 on RHEL3, and we upgraded to 8.2.1 last year. PHP/Mysql were not upgraded to the current versions though..

from the phpinfo page on my server, i have:

php 4.3.2 -> need to upgrade to 5

mysql 3.23 -> need to upgrade to 4

any pointers? I'm a begginer when it comes to ssh/linux stuff

thanks a lot for your time