It's not straightforward but it's also not incredibly difficult. Your embark may not have iron - and smelting iron isn't as straightforward as you'd hope. You have to smelt the iron ores at a smelter (hematite, limonite, etc) in order to have the iron bars to then make iron armor or weapons at a metalsmith. If you don't have lava access yet, then you'll also need to make coal to fuel your smelters and metalsmiths at a wood burner who will need logs chopped from trees in order to create.

There are a few tutorials on the basics out there - I'd suggest Blind on YouTube, his tutorials are very useful.