The most important thing is to keep in mind the deadline. If you want to have it count for 2016, you need to open the account and transfer the funds by tax day. Don't wait until the last day to do it, or you could run out of time. Setting up the initial account, and them verifying your information and transferring the money could take a few days.
First decide how much of a lump sum you want to invest initially. This will determine some of your options because the mutual fund will have a minimum initial investment. Many of the funds will allow subsequent investments to be smaller.
The beauty of a IRA or Roth IRA is that if the fund you want is out of reach for this initial investment in a few years you can transfer the money into another fund or even another fund family without having to worry about tax issues.
Now decide on your risk level and you time horizon. Because you said you are student and you want a Roth IRA, it is assumed that you will not need this money for 4+ decades; so you can and should be willing to be a little more risky.
As NathanL said an index fund is a great idea. Many also advise an aged based fund. My kids found that when they made their initial investments the age based funds were the only one with a low enough initial investment for their first few years.
Then pick a fund family based on the general low fees, and a large mix of options.
The best thing is that in a few years as you have more money and more options, you can adjust your choices.