Re: first build won't start (yet)
Welcome and enjoy.
One of the most common mistakes I see made by beginners is incorrect wiring. Make sure your ignition wiring is right. Remove the spark plug, ground it against the cylinder head fins and with the clutch engaged, rotate the engine via the pedals. The plug should spark. Next is fuel delivery. Is there fuel visible in the fuel line from the tank to the carburator? Is the fuel petcock open? (lever in line with fuel line).
The choke is on (closed) with the choke lever up, open is down. The small spring loaded button on the left side of the carburator is called a 'tickler' or primer. Use it sparingly, a few seconds depressed is enough. Close the choke, lever up, fuel petcock on and twist the throttle about half way then pedal with the clutch hand lever pulled in then release it. If all this proves to be fruitless, come back and let us know what happened. There are lots of other things that could be the problem, these are just the basics. We're here to help.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"