To play Marble Solitaire, simply click on a marble. (This also changes the color so you know which one you've selected). If you can 'jump' over a marble to the left, right, top, or bottom, so that you land on an empty slot, then click that empty slot. Your chosen marble will be moved to the empty slot, and the marble you just jumped over will be removed. Keep doing this until there is only one marble left. If you have a marble selected, but wish to move a different one, just click on the selected marble and it will return back to the original color. Now you may choose a different marble. That's it. Pretty simple.
If the rules are so simple, what are all the other options I see in the game?
Those options are there to enhance your Marble Solitaire experience, to give different variations, to help you when you are frustrated and to help you lose those last 10 pounds you've been fighting with all year. Well, so that is not all quite true, but 3 out of 4 ain't bad.
Game Mode lets you play the Classic (or standard) Marble Solitaire, while Reverse is there just to aggravate you. Instead of jumping over existing marbles, in Reverse mode, you jump over empty slots. When you land, the slot you just jumped over is filled with a marble. Work your way 'backwards' to populate the board with marbles to achieve the desired layout. To change the Game Mode, click the 'empty slot' beside the Game Mode name.
Layout lets you choose the starting pattern of marbles. All layouts can be solved such that only one marble remains in the middle of the board. (In Classic mode, of course. In Reverse mode, the lone starting marble will be in the middle of the board.) To change the Layout, click the 'empty slot' beside the Layout name.
Undo lets you cheat and back up if you've gone down the wrong path.
Restart is only to be used as a last resort, when all brainpower has been used and when you simply have nothing left to give. It'll likely be the button you use the most :)
Solve is the magic button. It alleviates all your frustration, shows you the light and lets you get on with your day. Note, solve will start solving the pattern from the beginning. It will NOT pick up where you have left off and try to finish the puzzle for you
Stop will stop the auto-solver, if it is currently in motion. This way, you can be sure you've started down the right path, and can then try to solve the rest by yourself. Oh, and if you let the solver run until there are only two marbles left, so that you can stop it and finish the puzzle yourself from that point... well, please don't make me have to find a sarcastic way to end that statement. So just don't do that, OK?
Want to give your brain a workout, without even realizing it? No, not by studying, doing homework, or reading a dry textbook. Do it the fun way - play a video game. Try one of the downloadable puzzle games at Thinking Is Fun. Lots of variety, lots of fun and lots of headscratching.