Step 1: The Notations
D-down or lower face
All of them to be turned clockwise, except they have apostrophes after the letter, like F', you should turn the front face counter clockwise.and if you had U2, you should turn the upper face twice, regardless on the way of turning. if you are given R'DRD' , you should turn the right side counter clockwise, down side clockwise, right side clockwise, and down side counter. Well, do this ''algorithm''6 times on a cube in solve state, you'll make it solve again. Trust me.
Step 2: The cross
Step 3: The first layer
Step 4: The second layer
and on the vice versa, do this:
do this until the whole second layer is solved.