A little more indepth on how it works:

Cryptocurrency is really just a public ledger. It uses cryptographic hash functions as a way to show proof of work for each block of the ledger. Every user has a copy of this ledger, and uses the one with the most computational work.

Miners listen for transactions, and then create a block (list of transactions) that has a sufficient amount of computational work, then it's broadcasted. They are rewarded with a new small amount of the currency that is brought into the economy. Also you should note that each block has a signature that proves this work and also includes the hash of the previous signature. Changing anything in the block would result in a different signature, which results in a different hashes on newer blocks. They are connected and this is why it's called a "Block Chain"

(Miners listen for transactions, while users listen for the block chain)

Making a fraudulent blocks is basically impossible as you would have to do the computational work that comes after the fraudulent block in the chain. This is because everyone is broadcasting their version of the block chain to others and if there are conflicting chains, then users use the one with the most computational work. You are also competing with many other miners on the network, so it becomes impossible to uphold a fraudulent version of the blockchain.