I agree with Rand Rover to a certain extent. Earlier today I wrote a long post about compound interest and investing, but having read through everyone’s posts and your responses, I deleted it because I didn’t think it was particularly relevant to your situation.
The bottom line is that at this point you do not need investment advice, but some personal finance advice might be useful. You might want to take a look at Elizabeth Warren’s books (All Your Worth, The Two-Income Trap) to get some good information about budgeting and saving.
I will recommend a basic approach to saving that is endorsed by most personal finance advisors:
First, save up a 6-8 month emergency fund that will cover your expenses in case you are unable to work. This fund can also cover emergency expenses in case your car, your house, or your body breaks down.
Second, contribute to your 401k plan up to the match.
Third, pay down your consumer debt.
Fourth, contribute to a Roth IRA up to the limit.
Once you are able to take care all of these, you can think about adding additional 401k savings or an individual investment account.
As far as your emergency fund, it should be in a liquid savings account. The interest isn’t much, but your money will be safe and available to you.
If you have at least a 20-year horizon until retirement, the 401k money should probably be in stock index funds, if they are available through your plan.
Once you get beyond these first steps, investment advice will be of more use to you.