Hi! Rather than start from scratch, let me just point you to this helpful site:
http://www.coindesk.com/information/Bitcoins are mined with each new block of transactions produced. Currently the block reward is 25 bitcoins, halving roughly every 4 years. Fees for transactions also go to the miners, but those are not new bitcoins but simply taken from bitcoins already in circulation. Blocks are produced on an average rate of every 10 minutes, though actual blocks can be a second apart or an hour apart based on the factor of chance in the mining process.
Miners are specialized hardware now (known as ASICs) that are operated by individuals or increasingly by large-scale industrial mining concerns. Anyone can get involved with mining, though in practice only those with very low cost electricity will likely see a profit. In years past you could mine with desktop computers, then graphics cards and FPGAs, but those days are long past.