It is important to have the correct set of strings fitted to your guitar, especially if you are a beginner. Until you build enough strength in your hands to fret the chords cleanly, light gauge or low tension strings are recommended. A reputable music store which sells guitar strings should be able to assist with this. Do not put steel strings on a classical guitar or it will damage the neck of the guitar.
This book shows you where to put your fingers and what techniques to use. Practice the examples on your own, slowly at first then try playing to a metronome set to a slow tempo, such that you can play the example evenly and without stopping. You will find that you can gradually increase the tempo as you become more confident.