Things you'll need:
Guitar (I felt it necessary to say so)
Electric tuner / piano or keyboard
Strings (you better know I mean guitar strings)
PS: MY 1st INSTRUCABLE!!!!
Step 1: String Maintainence
DO NOT tune higher than the standard note of the string. This may result in the string snapping and whacking your face and causing bleeding. :(
DO NOT pull the strings like a bow and launch arrows, you'll hurt yourself and shoot someone's eye out
To replace strings, connect to the bottom part (for the ppl who don't know its name), string thru hole on top of tuning knob aligning it in its slot in the piece at the to of the fretboard.
Spin the knob on the side of the headstock (where the tuners are) until tuned.
Strings are aligned as thickest on top to thinnest on the bottom.
Step 2: Tuning
from top to bottom (thickest to thinnest)- E A D G B E
Use your electric tuner / keyboard or piano to get he right pitch
You really only need to get the pitch of one string and then find the others in relation to it (see 2nd image).
Step 3: Neck
PS: a bent neck means you'll most likely have to buy a new guitar