Wanna make a Christmas tree with led lighting

I'm guessing here, Ted.  If they are all 3 Volt LEDs which have 1 kΩ resistors attached to one of their legs - and your power supply bus (short for omnibus - only one s ), is 12 Volts; then join all of the (+) together and all of the (-) together and connect them to the respective bus wires.

That way they will be in parallel and only draw 3 Volts each.

Max, Shoulda mentioned, the led are 9-16vdc. If that makes a difference. Wanted to use xfrmr acc power.  Ted

That should be fine, Ted.

LEDs will run on AC as well as DC power, although their life may be limited to 50 years service, rather than 100. 

Would you help me understand why I should parallel the wiring instead of series? If it needs to be parallel, it will be difficult to spread the bulbs around the tree, seems to me.  Perhaps I could search for hobby xmas lighting and use that. TW

If you join them in series, the resistance is the sum of the parts.  If you join them in parallel, the resistance is the same as only one of them.  Also, if they are joined in series and one fails, they all go out.  It breaks the chain.

If you're unfamiliar with electricity, then a set of Christmas lights would be the best option.  They are only a few dollars and are designed to do the job.

Max, gotcha. While I am a third grader in electricity, my search for led lighting strings just found those with those big honking bases and 22awg wire. On a 6-7" tree hard to hide those things. I may experiment with your system to see what I can come up with. Thx again. TW

Thank you Max for the excellent information about electricity in general. As for my Christmas lights, I took the easy way: Lemax light strings with their own power supply:

Allan, went your route on the tree. Maybe I give up too quickly   But why reinvent the wheel?  I have a method to get 4.5vdc from xfrmr acc, so that is covered. Thx again for the help. TW