If you want it to be step-up only (from 5v up to 12v), you can use the example circuit on the first page of the datasheet.
If you want to be able to set up a voltage lower than 5v (for example from 1.25v up to 12v), then you need to use the regulator in SEPIC mode, see example circuit on page 13 but you may need to adjust the inductor value for the narrower input voltage range and also note that it's a special inductor with two coils required, not a regulator inductor.
The datasheet contains the instructions about how to choose various components.
The output voltage is configured as explained in the datasheet, through two resistors. You can replace one of the resistors with a potentiometer, or you can put a potentiometer in series with the resistor to change the total resistance on-the-fly.
One of the resistors (R2) should be a value below 7 kohm, they recommend 6.19 kOhm, but you can probably go with a more standard value like 4.7 kOhm or 5.6 kOhm
The output voltage is basically defined by the formulas (page 7) : Vout = Vreference x ( 1 + R1 / R2) where Vreference is 1.245v OR R1 = R2 x (Vout / 1.245 -1)
So let's say you want to be able to adjust voltage between 1.5v and 12v and you pick 5.6 kohm for the R2 resistor ... then your R1 must be minimum R1 = 5600 x ( 1.5 / 1.245 - 1) = 1147 ohm and for 12v your resistor would have to be R1 = 5600 x ( 12/1.245 -1) = 48376 ohm
So the best solution would be to replace R1 with a 1000 ohm resistor in series with a 47k or 50k potentiometer, this way you'd have R1 between 1000 ohm (which sets output voltage to 1.47v) and 48-51kOhm (which sets output voltage to 12.58v)
You can buy one of those cheap seven segment display boards from eBay if you want to see the output voltage.
As for usb type c cable ... you can simply google for the pinout and connect your board to +5v and ground wires of that cable, nothing special.
Here you go :
https://en.wikipedia.org/wiki/USB-C#Connector_pinoutsVbus is your +5v , GND is your ground... all the other pins (wires, whatever) you can leave unconnected.
ps. you don't have to use exactly the same parts as the ones in the example circuits. If you can't find one just look for its datasheet and determine the most important "parameters" for that part and search at distributors like Digikey, Mouser, Farnell etc components with parameters very close to those of that part.
Or, read the notes in the datasheet where they explain why they chose that part, or what properties of that part are important, what they looked for when they made the selection.