To become the "Champion", you must answer all 15 questions correctly in a game taking up to the 1,000,000 mark. Easy mode is different to Normal mode in that there is no timer on each question, thereby allowing you to take your time when you answer.
To start a game from the main menu, click "Play" > "Solo" > "Easy" > "Next". Then select your character and begin.
The first five questions are the easy ones and even if you are unsure it is usually pretty obvious what the answer is by the options you are given. From here the questions become increasingly more difficult. Here are some tips for getting through all of the questions:
1. Select question categories that you know.
2. Use your lifelines wisely. Try to save them for the later, more difficult questions. That said, if you really don't know the answer using a lifeline is better than starting over.
3. Take your time to read the question and the answers. Sometimes a question can be answered through process of elimination.
4. Have a computer to hand for the more difficult questions. You will be able to search the internet for the correct answer before the timer expires.
If all else fails, you can always restart a game and try again with different questions.