It's honestly very hard to mess up while assembling a computer these days. Parts that aren't meant to go together won't fit, and you would have to try very hard (as in furiously rubbing your feet against carpet during assembly) to damage them with static electricity. Just be careful to not press on the motherboard like a madman; sometimes it takes a little work to plug components into it and lock them, and in some cases you will need to push fairly hard to insert them, but do not apply excessive force, take it slow and check what the issue is. The most intimidating part for a newbie is probably putting the CPU in its socket, just work slowly, read the instructions, think twice before doing and don't break anything and you'll be fine.
Just make sure to buy components that are actually compatible, e.g. don't buy a motherboard with an AMD socket and an Intel CPU, because that simply will not work.
It really isn't that hard