The best way to learn guitar is by having one-on-one lessons with an experienced player, preferably someone who is patient and used to teaching people how to play guitar.
If you're starting as a beginner guitar player you'll prbably start by learning some basic chords in each key. You'll learn about Major, Major 7ths, Major Dominant 7ths, Minor, Minor 7ths and 9ths.
Practise makes perfect so you'll need to put some hours in playing chords and memorising chord progressions. You may find it difficult at first to master the dexterity needed to move your fingers into position quickly enough and also to put enough pressure on the fret-board to produce a clear sound. There are many training aids available such as the gripmaster trainer. Google "gripmaster" to find a provider in your area.
You will then progress on to changing chords, transposing chords to a different key, power chords, how to read tabs (tablature) etc. There's a lot to learn as you move on to strumming patterns and rhythm guitar, lead guitar, guitar solos etc. If you are playing the electric guitar you should ask your guitar teacher to recommend some effects pedals to try out. There are plenty of second hand guitar pedals available on ebay.