How to make terrarian?

Try to locate some stones. There are many crevices that spawn from the world generation. Find a tunnel down or dig a tunnel down yourself.

Stone blocks will have a gray stony texture. Gather up twenty blocks with your pickaxe.

Next you will need to find a gel to craft torches. Slimes will spawn intermittently, any kind of slime will drop gel.

Swing at them with your pickaxe or your sword in order to defeat them. Every slime you defeat should drop at least one gel. Kill a couple slimes to get the gel you need.

You should have spawned next to some trees. Feel free to chop some down to get the wood you need.

Open your inventory and scroll down in your crafting menu to locate the workbench.

Left click the workbench icon to turn ten wood into a workbench. In order to use your workbench you only need to place it and stand next to it to update your crafting menu with everything you can currently craft. Make some torches by scrolling up to the top and clicking on the torch icon.

You will need one wood and one gel in order to make three torches. With your wood, torches, and stone, stand next to your workbench and scroll down to the furnace.