Re: crafting - I'll try.
In ED, there are two kinds of crafting: one you can do on your own, in your ship or SRV, the other one you need a crafts(wo)man for, which, in ED, are called Engineers.
On your own:
on your right hand side HUD, the same place where you got the materials inventory, you also got a tab labelled "Synthesis". If you go there, you'll see a lot of receipes, some in yellow, some in red. The yellow ones are in principle executable in your current situation (i.e., you can only refuel the SRV when you're actually inside the SRV, you can only synthesize small calibre ammo if you are in your ship and have multicannons installed etc.). Next to the receipe type, there are bobbles showing which level of the receipe you can currently execute, depending on your materials storage. There's basic, regular and enhanced (or something like that), with increasing demands and improving quality.
So, if you want to refuel your SRV or load up your Multicannon with improved ammo, you go to that menu, select the receipe, select the level and go. That kind of crafting uses materials (from Sulphur to Polonium)you can find from either mining (in asteroid belts) or prospecting (on planetary surfaces). If you drive an SRV, be careful - this is also the only method to refuel your SRV or reload its gun, so collect some SRV refuelling materials first (fortunately, they're easy to find) before you run out of fuel or ammo.
Engineers:
the secobn type of crafting requires you to visit an Engineer. Again, on your right HUD, somewhere on the bottom on one of the tabs, there's a button labelled 'see Engineers'. Select it, and on the front HUD, you'll see a list of the Engineers you currently have an invitation from. Getting an Engineer to do something for you is a longish process.
1) Invitation: You can't just show up at an Engineer's base, even if you know where it is - you need an invitation. For some Engineers, the invitation comes immediately to every new CMDR, for others, you need a sufficient reputation with another Engineer or a specific faction in the game
2) Favour: Next, you'll have to show the Engineer that you appreciate his/her work and are worthy of receiving his/her masterpieces. So you need to either do some stuff (like having mined 500 tons of ore) or bring them some essential supplies (like 50 tons of Lavian Brandy). The requirements for that are specific for each Engineer, and some of them are rather hard to fulfil.
3) Reputation: the Engineer won't craft his best stuff for any , Tom or Harry. Only if he gets to know you, through an extended business association, he will build his best stuff for you. Engineers can (not all of them) craft mods up to level 5. But in order to get a higher level mod, you'll need to have bought enough lower level mods or done specific work (like selling exploration data or bounties to the Engineer).
So when you finally can get something modified by an Engineer, you'll need materials for that. And this is where all that shiny stuff you can plunder from ships or get as mission reward comes into play. In addition to cargo materials, each engineering receipe (=blueprint) requires a certain amount of materilas that can't be bought or swapped, like exquisite focus crystals or modified consumer firmaware.
HTH