How to enter a 3x3 cube
Start by choosing the 3x3 cube from the solver grid. Work one face at a time and keep the cube orientation consistent while you enter colors. On a 3x3, the center stickers do not move relative to each other, so they define which face is white, yellow, red, orange, blue, or green on your cube.
Check each edge and corner against the real puzzle before starting the solution. If you rotate the cube in your hand, make sure the face you are entering still matches the face shown on screen.
Common invalid cube issues
A 3x3 can show as invalid when two stickers were swapped during entry, but some invalid states come from the physical cube. A twisted corner, flipped edge, or swapped pair of pieces cannot be solved with legal turns. These states often happen after a cube is taken apart and reassembled incorrectly.
Before assuming the cube has a physical problem, recheck the colors in good light. Red and orange, blue and green, or white and yellow can be easy to mix up on worn stickers or under warm lighting.
Solver versus learning a method
A solver gives you a route for the scramble in front of you. A beginner method teaches you how to solve future scrambles without help. Both are useful. If your goal is to finish one cube now, use the solver. If your goal is to become independent, use the solution as a reference and study the beginner guide.
Many beginners start with an online solution, then learn the layer-by-layer idea: solve a first layer, build the middle layer, orient the last layer, and finally permute the last pieces. The solver can help you recover when practice scrambles get out of control.
When the moves are generated
Follow each move exactly and avoid changing your hand orientation unless the instruction tells you to. If you make a mistake, pause immediately. Re-entering the current colors is more reliable than trying to reverse several uncertain turns from memory.