External power alongside h bridge

Hey all, sorry for noob question and all that, but I've scoured the Internet and I'm unable to get a clear answer.

I want to power a motor to move a sliding glass door, which obviously needs to have an external power source, and reverse ability. I'm still kinda fuzzy on the h bridge concept, the circuit with switches makes sense, but the ic form doesn't to me. I've really never been able to understand transistors fully.

My question in a nutshell is basically: What's the simplest way to power a 12+v motor, separate from the arduino, and reversible? Thank you for reading and answering, I'm thoroughly confused.

A motor will draw current at a given voltage depending on its specifications, speed, windings, load etc. The power supply and hbridge must be able to handle this current flow.

We need more details on the motor to recommend a bridge. The current ratings are just as important as the voltage. The time where the motor will draw the most current is when it is stalled or starting. The bridge and power supply must be sized to handle that.

A switch h-bridge, transistor h-bridge and H-bridge ic's at their core work the same way. If a 4 switch type hbridge make sense to you the leap to transistors is not that hard. Transistors are used like switches and arranged in the same fashion. They are turned on by supplying a small amount of power to their base or gate. The transistors or mosfets will sometimes need some other supporting circuitry to properly switch them on/off. An hbridge ic takes the bridge, driver circuit, and normally some self protection and combines it into an small integrated circuit.

Find out some details on the motor! It all depends on that.

If you don't need speed control, 2 double pole relays might be the simplest and cheapest way to go.