Try this: (If one of the great gods of wiring wants to jump in with a more betterer solution please feel free)
This is in parrallel rather than in series which has the advantage of using a smaller power supply and it's easier to make them light individually by assigning a single LED contact to each fingertip (one will have to double up). I also went the 6 and not 7 since the 7th infinity gem isn't cannon.
1 x 6 array
+----|>|---/\/\/----+ R = 150 ohms
+----|>|---/\/\/----+ R = 150 ohms
{6v} +----|>|---/\/\/----+ R = 150 ohms
+----|>|---/\/\/----+ R = 150 ohms
+----|>|---/\/\/----+ R = 150 ohms
+----|>|---/\/\/----+ R = 150 ohms
each 150 ohm resistor dissipates 60 mW
¼W resistors should be fine for this application
together, all resistors dissipate 360 mW
together, the diodes dissipate 396 mW
total power dissipated by the array is 756 mW
the array draws current of 120 mA from the source, which is 4AA batteris.
LEDs in this diagram are white LEDs with 3.3v of diode forward voltage
If you want to use colored LEDs those use less power, around 2.2v. You can work it out on this
LED Calculator and then do the wiring diagram option and it will give you pictures of how to lay it out.
To buy: Wire, 6x white 3v LEDs, 6x 150 ohm resistors (brown green brown), tape or a battery compartment for 4x AAs.