Server management expert

Hello, I have recently rented a server from my hosting provider to place the websites I made for my clients. This server has linux and parallels panel installed and it will be used nearly exclusively to host joomla, magento and maybe wordpress websites. Not having any knowledge of server management I am looking for someone who can help me on an ongoing timeframe to manage the server and resolve any problems that occur. The first problem that must be resolved is I noticed that the websites I transferred to the server (all built with joomla! cms) are too slow to load. Even a fresh new install of joomla takes an unacceptable time to load. I need to fine tune the performances of apache and mysql of my server to resolve this problem. Later on some hardening of the system will be required and eventually also updating the system. For every job I will require the hours needed for it to be completed before starting and if approved the person must stay in that budget to continue working on future jobs. For any questions please don't hesitate to ask. Thank you. Best regards