Here's a guide to crafting posted by a player named Beacon on the official forums:
Step 1 - Search the open world for exobits, you'll need 8 of one type or 4 of two different types to make an exobyte
Step 2 - Purchase the best plans you can from the vendor next to the crafting table, the ones you buy with marks of triumph are the best ones you can purchase. Better plans are supposed to drop in instances and in the open world but I haven't seen this yet.
Step 3 - Salvage useless green, blue and purple drops for the remaining parts of the plans you want to create. It seems to give you a random piece, so don't go buying and destroying purple drops just yet because your gonna get the same thing from greens. You can also buy certain white pieces to complete plans from the vendor.
Step 4 - Click on the plan you want, add the right exobyte and the right pieces and your done. If you made an armor node, unequip the armor piece and move the node to the armor, if you made sodas they are ready to go right away.
The old white drops are still useless, and you cant salvage gear bought with marks.
Equipping an armor piece with the right color node, gives you the bonus the of the node created, plus an affinity that is based on the item score of the armor your adding it too, it's listed in the armor stats.
You can't remove a node once it's integrated, but you can replace it with a better one.