I am in need of steel, but when I made the blast furnace and opened it up, there was a bunch of stuff that I have no clue what the purpose is. There is something about fluids, and heat, and I just don't get it.
The Blast Furnace needs three things to run, iron ingots to make the steel with, heat and air.
Iron ingots are the simplest, that's just your normal vanilla iron. If you forget it then it might look like the blast furnace isn't working as it will stop needing heat. Iron goes in the slot to the left of the arrow in the middle of the GUI.
Heat is produced from heat generators, such as the Solid or Liquid Fuel Fireboxes or the Electric Heater. You have to make the heat producer's red square touch the Blast Furnace's red square. The wrench is your friend here to rotate the square if you placed it down the wrong way. The amount of heat purely determines how long it takes for the Blast Furnace to warm up: an Electric Heater can go up to 100 HU (heat units) but that won't make it go any faster than 10 HU to actually make the steel once it's warmed up. It can't run without any heat at all though (and will cool down over time if not given any).
Air is made by putting (empty) Universal Fluid Cells in a compressor. They go in the slot in the bottom left of the GUI (below the tank), and will be returned empty once the air is removed from them (so they can be reused).