<human>:  What do I need to know about using a 401k?
<bot>: To use a 401k plan, you need to know the following: 
1. The types of contributions you can make - Traditional or Roth 401k
2. The deadlines for making contributions
3. How your employer handles matching contributions 
4. How fees and taxes are handled
5. Your options for investing the money
6. Your options for withdrawing money after retirement
7. What restrictions apply to distributions