Where is "VDD" aka "positive" on the Arduino Uno R3? I can locate three ground "gnd" . Does Arduino have a description of the pins and holes on the Arduino Uno R3? Thanks.
Vdd can be 3.3V for devices that need that, or 5V for devices that need that
The microcontrollers forum has a sticky post with a nice picture for what all the contact locations are.
CrossRoads: Thank you for your response. Do you mean the female 3.3V and the 5V "holes" in the "POWER" whatchamacallit? I'm new to all this. I see on that sticky post you mentioned that "VCC" is located near the "MISO" and "GND" and isn't "VDD" the same as "VCC"?
Paul__B, thank you for your answer and diagram. A herculean task if ever there was one, my good man. But an angst has overtaken my ever analytical mind and I am wondering if you are referring to the black dot with the right angle line connected to the red rhomboid with the "5V" in it that is opposite the "MISO" pin? They are contained within the rectangle with the six white dots in it? Did you know that another post calls it the "VCC"? Do you think "VCC" and "VDD" are synonymous?
Sinusoidal PWM? 
Yes, 3.3 & 5V in the power header.
There is also the same 5V on the two 2x3 headers.
Vcc and Vdd are used interchangeably to represent power.
One has origins in MOS/CMOS logic, the other in BJT logic, you can google it.
CrossRoads thanks for the reply. "There is also the same 5V on the two 2x3 headers." You mean the "two 2x3 headers" are the six pins with the letters "ICSP" near it and the six pins with "AREF" near it? Thanks.
nervousenorvus:
Paul__B, thank you for your answer and diagram. A Herculean task if ever there was one, my good man.
Not mine! They belong to a fellow who goes under the moniker of "PighiXXX". 
nervousenorvus:
I am wondering if you are referring to the black dot with the right angle line connected to the red rhomboid with the "5V" in it that is opposite the "MISO" pin?
I think you really should update your "Profile" on the discussion board here to explain from where you are contributing and any other details of interest; perhaps your occupation!
The main "power" pin which corresponds to the supply voltage for the ATmega328 chip is the one labelled "5V" on the "Power" header socket. This can either be used to supply a well-regulated positive supply of 5V to the board, or if 5V power is supplied by USB, or a 7 to 12V supply to either the 2.1 mm coaxial jack or the "Vin" terminal on that same "Power" header socket, then you may draw a limited supply (no more than a couple of hundred milliamps in total) from the "5V" terminal.
The "3V3" (3.3V) terminal is an output capable of supplying 50 mA or so to an external device requiring that supply voltage. You cannot supply power to the board by that terminal, and there are considerations when interfacing 3.3V devices to the Arduino signal (digital) pins.
nervousenorvus:
They are contained within the rectangle with the six white dots in it?
That connector is not intended for supplying power to the board (except when nothing else is connected and the board is being programmed by an AVRISP module). You can if you like use that connector however for attaching a device which utilises the SPI interface.
nervousenorvus:
Did you know that another post calls it the "VCC"? Do you think "VCC" and "VDD" are synonymous?
They are. As CrossRoads mentions, the terms Vcc and Vdd originally refer respectively to "Voltage supply for transistor collectors" and "Voltage supply for MOSFET drains" usually presuming of course, NPN transistors and N-channel FETs. Most digital ICs of course use MOSFETs, but we tend to hybridise these in circuits with bipolar transistors, so both terms are reasonable.
This question is connected to the OP's other Thread and I can't understand why he didn't just ask the question there.
In any case I had earlier provided an answer in the other Thread.
...R
OK, so I should - as I usually do - have researched his other questions rather than answering directly. 
Paul__B:
OK, so I should - as I usually do - have researched his other questions rather than answering directly.
Jeez - the very last thing I was trying to do was criticize you.
...R
Robin2:
Jeez - the very last thing I was trying to do was criticise you.
No, just an observation. Generally, I research "newbie" questions, to see what they are on about, and craft my answer to their more complete project rather than the isolated and often obscure query.
Last week, I was working on small browser solution to locate pins on Arduino: http://arduino-uno-schematics.divshot.io/ - it is not yet fully functional (selecting a pin, sorting the pins, etc.) - but feedback on this idea would be nice. I have heard upverter or Fritzing provides a similar function to some.