problem starting car

i know this might be a kinda newb question but my sisters car wouldnt start one morning and so i gave it some gas and popped the clutch to start it and it did but it makes some really loud screeching noise whenever the car starts...this happened even before the i did that to the car...its been making that noise for about a month now...its a '00 Nissan Sentra XE...does anyone know what could be the problem? any help would be appreciated...

loose alternator belt... unless you have a serpentine belt. It could be a failing alternator. Either way it sounds like the alternator was failing and didn't charge the battery last time you had it running, so now it won't start. Once it running it makes a squeal. With the car running find the alternator and see if its spinning at all, or at least spinning as fast as the belt. The bearings could be bad causing it to drag down.