Asking questions is the first step to enter a learning phase. Best of luck in your journey.
As others have indicated, Vanguard is a good long term option. There is a fund for most areas that other company funds (Fidelity, etc) map to.
And VTSAX/VTSMX is a nice option..especially for the long term.
But, before you dive in, there are a couple of things you may want to think about.
+ When will you need the money back? If you need the money back in less than 3 months, then a CD is best perhaps....in 5 years, then VTSAX is good enough, .....
+ What is your tax bracket? If you are in a high tax bracket, then look into some of the tax managed funds that Vanguard provides....VTCLX, VTMGX, etc.
+ What is your asset allocation and what is your financial plan? I would just pay $250 to a Vanguard financial planner, get a thorough look into your finances and goals and form a plan first before investing. The plan may lead you into different investments rather than everything in one bucket.
And MOST IMPORTANTLY, if you decide to withdraw money, please look into the REDEMPTION cost for each fund. When you withdraw, it is not just taxes that is paid...there is a penalty depending on the fund. For example, for FMCSX (a fund you own), here is the redemption cost.
http://financials.morningstar.com/fund/expense.html?t=FMCSX®ion=usa&culture=en-US Redemption
0 - 30 Days 0.75%
More Than 30 Days 0.00
So, to avoid redemption cost, I would stop buying this fund for 31 days and then sell it so that there is no redemption cost.
Hope that helps.