Use the central dropdown menu to select what you want to create: Items, Weapons, Tools, Food, Armor, Blocks, Ores, Music Discs, Soundtracks, or entire Biomes.
Set the name and balance the stats (damage, durability, etc.). Upload your .png (textures), .json (3D models), or .ogg (audio) files. Alternatively, use the Built-in Pixel Editor to draw textures on the fly, even using Vanilla items as a base!
Click on the recipe buttons to open the Crafting Table or the Furnace. You can place Vanilla ingredients or use other custom elements you've already created to build a true progression tree.
Press " + Add to Mod" to save it to your mod. When you are ready, use the side panel to choose the Minecraft version and click on Generate Mod (.jar). Wait for the compilation to finish and download the file!