Hi there,
String bends are tricky when you start out but stay with them becuase they are one of those things that separate the boys from the men (so to speak). First of all you can either bend up or down (to you head or towards the floor), experiment and find which is best for you when you are starting - you will pick up the other way easily once you start to progress. Some people bend with their middle finger and add support with their pointing finger - effectively using two fingers on the bend. Personally, I only ever bend with two fingers if it is an extreme bend eg 1.5 tones or more with added vibrato. Things to watch for are bending on the high E, you should bend that string towards your head otherwise the string will go off the side of the fretboard. Likewise, ifyou bend on the low E then you should bend towards the floor to avoid the same. If you experience buzzing it is probably because the action on your guitar is too low or you have a slight bow on the neck - you can adjust string height and the truss rod to iron that out esily enough.
No doubt some of the other guys will post a lot more tips, my personal #1 tip is to add vibratto to your bends. Also, practice using different fingers and neck positions and find the tone you want to bend to and train your ear to be able to bend to the correct tones. It all takes a time but you will find it comes together as you improve over time.
Hope that helps.