this is why i often advise newcomers to try adding some small single mods first, to familiarise themselves with the structure of files and so on, before diving in the deep end and installing a huge pack (sure, CUP is an awesome pack with thousands of mods, but i can see how it can be quite intimidating for a newcomer.
just follow the instructions that are supplied with most of the mods for installation, and rather ask about it in the relevant thread, than me trying to answer all your questions here. if you are unsure of an installation step, it's much easier to ask first to eliminate any doubts, than to muck it up.
either way, even making mistakes is a good learning exercise for most.
something that many people forget about IL-2 modding, is that this game was never designed for mods.
the game was basically hacked to allow it, and even so, there are often workarounds needed to get things to work properly, and yet other things simply won't work together.
this is something a lot of new folk don't realise, and they expect everything to 'just work' as it does for other games which were designed from the outset to cater for mods.
which is why you might see me or other admins getting a little upset when newcomers get pissed and blame us for not making everything work 100% from the word go.
it means that new people simply need to take a little more care and do some reading before embarking on modding IL-2. it's not simply a 'plug 'n play' option - that is just the nature of this game.
as long as you make regular backups before making any changes, you'll be fine.