The most basic part of Armstech crafting will be crafting various kinds of Assembly Elements. We'll start by crafting an one of the default schematics you got when you selected Armstech, which when you click it will tell you it requires 2 x Silica, 2 x Desh, and 2 x Conductive Flux to craft.
To determine which event skill the products you will require come from, hover over the listed material. When you take a look at the tooltip by hovering over them, The Silica is noted as Grade 1 Scavenged Part and the Desh is Grade 1 Scavenged Metal both of which come from Scavenging.
White-bordered materials are a bit different you can either send your companions to collect them if you have a mission available for them, or buy them straight from a supplier called the Crew Skills Trade Supplier in the Strongholds & Crew Skills area of the fleet who sells them quite cheap.
As soon as your buddy is completed crafting your schematic, the product will reveal up in your inventory and your crafting level will go up. This Is Cool are the foundation of Armstech crafting while they're pretty useless by themselves, you can integrate them with other materials to craft real products.