my question is about my ford focus 2001 zetec?

hi i just bought a ford focus 2001 zetec and i so hope u can help me
when i bought the car things were ok and now that i have left the car on the car park for 3days and went 2 start yesturday to leave it runing for 10minuts a squealing or Squeaking dont know witch word would describe the noise better anyway
the noise comes from the engine from the left side as u face the engine can you help me out by telling me what it is? is it the timebelt? hope u can help me thankz
please do reply me on my add on V_BULLET@HOTMAIL.COM many thankz