Why 2x2 cubes are different
On a 3x3, centers define the face colors. On a 2x2, there are no fixed center stickers, so orientation comes from the relationship between corner pieces. That is why careful color entry matters: the solver has to infer a valid cube state from only corners.
The puzzle has fewer pieces than a 3x3, but it is not just a toy version. A scrambled 2x2 can still require a planned sequence of turns, especially if you are not familiar with corner orientation and permutation.
How to enter the colors
Choose the 2x2 cube size and enter each visible sticker. Keep the same top and front orientation while moving from face to face. If you rotate the cube, pause and make sure you are still entering the correct face on screen.
Because every piece is a corner, a single wrong color can place a corner in an impossible position. Review all eight corners before starting the generated solution.
What invalid states usually mean
Invalid 2x2 states are commonly caused by color-entry mistakes, but physical issues can happen too. If one corner was twisted by hand, or if pieces were removed and put back incorrectly, the cube may not be solvable through legal turns.
If the solver reports an invalid state, compare each corner on the real cube with the colors you entered. Fixing one incorrect sticker is often enough to make the state valid.
Learning from the solution
A 2x2 is a good puzzle for learning how corners move. After using the solver, try watching how the last few turns affect corner orientation. That can make it easier to understand beginner methods later, including the ideas used on a 3x3.