Hello,
I've created a wallet using Armory bitcoin and (as it is in default settings) I immediatly tried to transfer my bitcoin using the adresse under "Received bitcoins".
Does Armory need to be online so that this works (sended to incorrect adresses) or is the transfer from one wallet to another long due to the blockchain ?
If i've lost my money you are allowed to make fun of me (~100£).
No you don't and will try to break it down why is that.
Bitcoin was made that there are known pairs of public and private keys, but we have so many combination which makes it nearly impossible for somebody to random generate keys and generate your key, although this is possible but chances are really really low for that.
Blockchain is just data structure. Each block contains transactions and like a pointer to previous block. Every node of the network keep copy of this ledger and thus your coins are not stored on your device, in fact number of your balance is written into the blockchain (inputs and outputs exactly). Everybody can create transactions with your balance, but then they will show up as invalid because they wouln't have the private key to sign that transaction and prove that they are the real owners. Many of this is simply done behind the scenes so you actually don't have to think about these things. But one thing is for sure keep your private keys safe.