# What is the deal with input voltage?

Let me tell you right off the bat that I am new to electronics, more specifically the creating of electronics. I recently discovered a project that I would like to make, a pocket power supply(link at end of question). I gathered up all the parts for it as it didn't work( I.e. I tried prototyping on breadboard and found no sign that it was working), and after multiple retries, I noticed the Vin and Vout on the project, or rather focused on them more as the possible problem to the circuit. I am not sure if both sets are supposed to be grounded, or rather one is the positive voltage of the battery and another is the negative terminal. I am honestly confused by this and would like another who is well experienced to cover this. Thank you and here is the link to the project.

Vin connects to the battery. The upper connection goes to + and the lower one to -. Vout is the output: it goes to whatever you're trying to supply power for. The upper connection is + and the lower one is -.
Take a reference rail(probably the one running on the edges vertically) on your breadboard and label it as GND(in your mind!) .The + part of Vin comes from the + terminal of the battery and - of the battery goes to the GND on the breadboard. Now you have a reference terminal where the - of the output can be connected,with the + of the output going to the device which you want to connect to the power supply.