I want to build this project. I probably have almost all of the parts except maybe the IC. It is really confusing. I think something is missing, because it's not making sense to me. It seems like part of the schematic is missing, and I can't figure out where the fingertip goes in the schematic.
The finger goes over D1 and D2 (LED and photodiode) as the picture with finger shows.
Does this need any software to work? Or will it just work by connecting all the components? I don't have much experience with ICs. I don't know how they work.
It needs software which appears to be supplied in a zip file.
The microprocessor part , which is based on a pic processor, switches on an IR led and counts and displays results on 3 digit led display.
There is another part of the circuit based on a dual operational amplifier chip which is connected to a photo diode, interprets the pulses, and sends the information to the microprocessor.
Note that the pic is not an Arduino.
There are several versions of this project on the website. Are you planning to use and Arduino or a PIC? Are you
planning to use the EasyPulse sensor, or are you planning to build the sensor and circuitry that's shown on the breadboard?
I have no idea which version? The only thing I can see is 2 schematics, and a picture. That's all the information I have. I don't see any zip file, or any other details on the project. 
Edit:
I see a PDF to download but it won't let me download it. I don't see a zip file. I don't want to use that easy sensor. I don't think I was going to use the Arduino either right now. I wanted to build the one in the picture below, on a breadboard.
Use a different web browser.
For a PIC project you will need a PIC programmer and PIC software on your PC/Mac.
I guess I need to pick an easier project then, because I don't even know what a PIC programmer is. Maybe I can use Arduino instead, but I still don't know the code.
Do you ever try Google?
Wowsers! Every time I visit instructables they somehow manage to make that site even worse.
@adele, the author provides a slightly more navigable site with an Arduino version here...