EDIT: Solved (originally - Looking for some electrical help - funky dimmer switch installation)

[purbeast0]

I got 2 new dimmer switches that are LED compatible and am trying to install them. One of them installed no problem as a single pole installation. The other one however is a pain in the ass. This is the manual here for the one I got.

https://m.media-amazon.com/images/I/91cOfo1WwLS.pdf

I'm going to call the screw on the top right #1, the screw on the bottom left #2, and the screw on the bottom right #3.

Well when I took off the old dimmer switch, it had 1 red wire going to #1 and 2 black wires going to #3. There was also electrical tape around the outer edge of the dimmer to cover all the screw posts. There was no ground wire or anything screwed into it. I didn't really pay attention to this at the time because I thought I'd install it the same as the other, however there was no ground wire so I knew something was up.

Since I'm a noob to this I have tried various installations. If I don't have the 2 black wires on the same terminal, the rest of the lights on the circuit don't work. At one point I had the red wire to #1, black wire to #2, and black wire to #3, and some weird stuff was happening with the switch and the other lights on the circuit as well.

But then I tried putting the red wire to #1 and the 2 black wires to #3, and it worked, however the switch is backwards. I push it down, and it turns off. Up and it turns on. The dimmer on it however is working in the normal direction.

I also tried putting the 2 black wires to #2 with the red wire on #1 and that didn't work. The rest of the lights on the circuit worked however the lights this connected to did not work.

I swapped the red/black wires and put the red wire on #3 and 1 black wires on #1, however the switch was still backwards.

Aside from flipping the switch upside down, which I don't want to do because the dimmer control would then be backwards and on the opposite side it is on now, is there anything I can do to fix this? There is not another switch on this circuit that I am aware to, and prior to messing with this at all, the way the original switch was, it was working as expected.

EDIT:

Just fixed it. After googling and stuff I realized it was still just a normal single pole and I connected the red wire to #2 and 2 black wires to #3 and it works just fine now. So much better with this dimmer because the LED's now dim lower than with the old switch. They are now much more comparable to the $15 halogen bulbs I am replacing.

 

[Paperdoc]

What you did lastly is correct nearly, but you certainly know that already. The why? part:
The dimmer switch is supplied as a double-throw switch (also called 3-way) but you CAN use it as single-throw if you simply do NOT connect a Hot supply line to one of the input terminals. That is what the Single Pole diagram is about. (They should not have used the word Pole there - it misled me, too.) Think of the terminals as: your #3 is the output; your #1 and #2 are two possible inputs from Hot lines. The switch simply chooses which Hot Input is relayed out to the Output on #3.

In your particular case, the previous installer used a common short-cut. The wires in the box are ALSO used as a junction point that can feed power from an incoming Hot line out to further boxes in the circuit. The "proper" way to do that is to make that junction (including a short pig-tail lead) separately at the back of the box, and then use the pig-tail to bring power to ONE of the Inputs (#1 or #2). WHICH input terminal you use for this will determine whether the switch is right-side up or upside-down, as judged from which way its action works. What the previous installer did instead was to skip the separate junction and twist the incoming Hot and to-the-next-box wires together and put them both under one if the Input terminals to hold them together there. They just omitted the pig-tail lead.

Why did I say "nearly"? Terminal #3 is the Common terminal, used here as OUTPUT from the switch. #2 is one INPUT, the one that will make the switch "right side up". #1 is the other INPUT IF you were using a second such switch on this same lighting circuit. But you are not doing a 2-switch-location system, only doing a Single-Throw installation. so what you did is reversing which terminal is which, but it still works just fine for what your circuit does.