¡Bienvenido!
Where the IR library is on the hard disk? The tree on the left pane is part link, part real files.
- Have you run the Arduino IDE once and declared the SketchBook folder? —see §1.2. Install the IDEs of the Boards
- Is the IR library inside the library folder inside the sketchbook folder? —see §3.3. Add User's Libraries
- Is the IR library a user library —you've wrote it— or a standard library —supplied with Arduino? —see §5.2 Manage the Libraries for Compilation
If you new to the Arduino world, I'd recommend to go step-by-step and start with the standard Arduino IDE before switching to Xcode, which is a very rich IDE.