First let me say that if you're looking to assemble your own from a kit that this is NOT a kit for beginners. This kit uses LEDs in an unconventional way and soldering them is not particularly easy and ruining the LEDs is. Purchase a kit and assemble at your own risk! I have soldered literally thousands of LEDs this way so at this point I make it look easy.
What's in the kit.
1x Ornament Board
1x Power Switch
1x AAA Battery Holder
20x Slow Flashing 0807 RGB LEDs & 5x Spares
Below you'll find detailed step by step instructions but before we get to that here is a quick break down of what we're going to do.
Prep the LED & Power Switch pads.
Solder 1 Side of the LEDs & Power Switch.
Solder the other side of the LEDs and clean up the first.
Put AAA Batteries into the Battery Holder and put it through the pin holes then slide the switch up to power on.
Verify that all of the LEDs light up and are changing color. If an LED stays red or seems to be entirely out of sync with the rest it is likely burned up and needs to be desoldered and replaced.
If left on long enough all of the LEDs will be go out of sync so being out of sync only applies to the first couple of seconds.
Verify that all of the LEDs are working correctly.
Remove protective film from the white pad then place the battery holder back into place.
Solder the battery leads to the board
Power on the ornament again and verify that it still works.
After verifying it still works snip the excess leads.
Place on tree and enjoy!
These LEDs are Slow Random Flashing RGBs, generally they tend to change colors in sync for the first few seconds but not always. As long as the LED is changing colors it is still considered a good LED, if it's not changing colors at all then it is a bad LED.
Prep The Pads
Start by prepping whichever side of the LED foot print you prefer. I'm left handed so I prep the left side. You want to be a fairly sizable glob of solder on the pad, you'll need it to bridge the gap between the pad and LED.
This is what it should look like.
And this is what it should look like with all of the pads prepped. Don't forget to prep the power switch pad but do it the normal way. The power switch has posts that help position it into place so putting too much solder on the pad will make it difficult to place.