There are 2 main ways to get villagers in Minecraft, but they do not spawn in the sense of traditional mobs. They don't just appear no matter what you do. The methods are: 1. Find an existing village in a plains, desert, or savannah and move them to your home (I find mine carts to be the easiest for this method). 2. Wander around your home at night with a couple of gold apples, a few splash potions of weakness, and some blocks. You will eventually find zombie villagers (green like zombies but villager skins) coming after you. This may take several nights. Kill anything that is with it and then hit it with the splash weakness. After that, feed it a gold Apple. You will hear thunder and it will shake. After a while it will become a villager. The blocks are to keep it safe. I build a small dirt own and lure it in, then run out and finish the walk to trap it. Make sure you put a roof on it as the sun can still burn it until it fully transforms. Also, zombies will attack him after he transforms. As much as it sounds harder, unless you have a village nearby, it is typically far faster. If you get a farmer and any other, you can then give the farmer wheat/carrots/potatoes and it will feed the other one. Once full, they will try to breed with each other, if you have what the game defines as houses. For that I suguest you go to the mc wiki and read the villager breeding section.

Apples drop from despawning oak and dark oak trees. Just chop the wood and let the leaves do their thing. As for blazes. That can really be just a lot of searching. I recommended bringing some obsidian and flint with you. This way you can set up portals along the way and surround them with a dirt build on the overworld side. That way you have a relatively safe place to go if you get in trouble so you can eat and recover. Also, while a bit time consuming, if you make a few ender chests, you can load one at your home and put down another at each of those portals so you can refill your food, replace broken armor/weapons.