Colors = jobs. Length of password = how many entries in the sequence, which should be 5. The Secret Code part comes from Mastermind being a game about determining a secret code encoded as a sequence of colored pegs/marbles, and only receiving feedback on if your code is partially correct or not.

You have a pool of jobs (probably more than 5) and 5 places to put them. The game tells you Hit if a job is correct but in the wrong slot, and Critical Hit if the job is correct and in the right slot. Otherwise you know the job is wron and thus can't be in the right placeg. You only win by successfully deducing the entire sequence. These rules are simple, and you use them to change your guesses, and glean more information from the next guess. It's not too different from solving treasure caskets. You need to play more logic puzzle games if you can't understand a simple game like this.

Purble Place is a Microsoft game built into the install of most Microsoft Windows 7 installations. It is a bunch of childrens' games centering around solving puzzles or memory exercises. One of the games has a creature in a dressing room, with several facial features, and several colors to choose from of each feature. It is another variation on Mastermind, but you can select how may facial features and colors are in the pool. It also gives you more hints, like which specific piece is wrong, rather than just how many you have correct. WIthout specific wrong answers being pointed out, you can limit how many changes you make per guess, which will narrow down which slots are correct and incorrect.