There is no simple answer because each mods machines behave differently in terms of automating input & output. The ME interface can accept items ejected from an adjacent inventory, but will not actively pull items out of an adjacent inventory. Also, it will only push items into an adjacent inventory with an auto-crafting pattern in the bottom row of spaces in the GUI. Setting the export config on the left slots will only tell the ME system to keep that # of items in the interface itself in the slots on the right. This was probably the most confusing thing about starting to learn the basics of AE.
To actively pull items, use an import bus: basic will pull everything 1 at a time, precision can be set to pull either 1 or a stack at a time & can be filtered to only pull certain items, fuzzy is like precision but can also be set to consider damage values.
To actively push items, use an export bus, same 3 types as the import bus.
To make things even more confusing, some of the blocks you want to interact with have sidedness. TE machines let you choose which sides are in & which are out, but they can't be both. IC2 machines all sides are in, & you can use an upgrade to choose which side to auto eject from, so you could use 1 interface to push crafting pattern recipes & accept the finished product. With a vanilla furnace, you pull the cooked stuff from the bottom, load raw stuff from the top, & add fuel from the sides. Some machines are smart enough to only let you pull finished items, some aren't.
Everything I know I learned from watching tutorials on youtube.