0) Learn Java. You need a fairly descent understanding of all of the basics, and some of the more advanced things like Lambdas. A good quick test to see if you understand it well enough is to look at the code for an open source mod and see if you can work out how a particular mechanic works. Pick a mod loader, follow its getting started directions, set up its example/getting started mod to get most of the boilerplate stuff done, and start writing your own code. If you want a softer start then you can look into making Resource Packs and/or Data Packs, as mods use those/expand upon those existing systems (Data Packs can make dimensions now, for example). You can also consider contributing to open source mods and hopefully getting some tips there. More on reddit.com

Just have fun and play in creative More on reddit.com

Honestly it comes with a really cool ponder system so just mess around with stuff and you’ll figure it out yourself. As for mod packs I recommend create:optimised. Super simple and runs really well More on reddit.com

The short answer is: the Ponder system is your friend. If you hover your mouse over any part from Create and hold w, you get an animated tutorial for how to use that part. There's also a button in your pause menu that looks like a pair of goggles, that allows you to browse every tutorial in game. The longer answer is, to get started with Create in survival, collect a bunch of iron and andesite. Craft some iron nuggets and andesite together to create alloy, and you can use this to create your first machine, a mechanical press. You can power it with a handcrank, which turns the power of your massive biceps into mechanical force. The press turns ingots into plates, used to build more advanced machines. Any item called "Mechanical X" in JEI is a machine used to either process items or affect the world. A good next step would be to make a mechanical mixer and a basin, which allows you to mix alloy together more efficiently. But the mixer needs to turn at a high speed, higher than your arms can provide... So you'll have to learn how to make a windmill or waterwheel, and how to use shafts, cogs, and gearboxes to connect the machine to the power source. Once you get a handle on the basics, you can think about building assembly lines. Mechanical belts can be used to transport items through the world, and funnels and tunnels move items into machines or storage, and route them across your belts. A good first contraption is an automatic tree farm. There are lots of ways to build one, but by using mechanical saws to chop the trees, deployers to replant the saplings, and some belts to move logs around, you can to get a fully automated supply of wood, which could mean a fully automated source of charcoal, which could mean a fully automated source of power... etc. Dig through the ponder tutorials and experiment. More on reddit.com