There are 2 common sorts of IR detectors. The simplest is a PIN photodiode, which has 2 leads. It needs an amplifier and signal conditioning circuitry to do anything useful. I use one with an amplifier and an oscilloscope to see what signals are generated by IR remote control units.
The other sort is a 3-wire IC containing a photosensor, amplifier and detector. These are designed to work with IR that is modulated at a particular frequency, most commonly 38KHz (which is what most IR remotes use). This type can be interfaced directly to an Arduino.
So if your detector is a simple photodiode, then I suggest you buy one of the 3-wire 38kHz IR detectors to make your life easier.