If you simply go outside and hold in your hand something of standard area, like a coin, atmospheric pressure is nothing but the weight of all the air above that coin, in a very slender cylinder, going from the coin up to outer space.
Of course, since some of the air can sneak in under it and push up, you don't feel that weight.
Temperature of air is like temperature of anything.
If you heat it, it gets hotter, and if you cool it, it gets colder.
Air gets heated because the sun shines on the ground, making it hot, which raises the temperature of the air.
Another way to make air hot is to squeeze it.
Like if you take a bicycle tire pump and squeeze some air with it (increasing its pressure), you should notice the pump gets warm.
The opposite happens too. If you let it expand, it gets cooler, but those only happen because the air in the pump is sort of insulated from the outside air.
(There's a big word for that - "adiabatic".)
Now in real outside air, the air doesn't stay still.
Some of it moves up, and some moves down.
The air that moves up goes to a place of lower pressure because there's less air above it, so it expands and gets cooler.
Likewise descending air gets warmer, for the same adiabatic reason.
So, for example, the air is much warmer at the bottom of the Grand Canyon than at the top.
Put all these together and you'll start to understand how weather works.