Hello.
I'm totally new to all this and really very much interested.
I've browsed the web to understand what this whole network is and have found many things but nothing that seems simple enough for me to understand the fundamental structure in which the network is based. So, as a newbie, I'm asking the following questions:

• Are bitcoins generated from scratch?
• Is the value of each bitcoin changing over time and if it's not, then this is why the number of bitcoins awarded each time a block (if I'm saying it right) is decoded changing every 4 years?
• Why are bitcoins given to individuals, for what kind of work?

From the little things I've understood, bitcoins are given when a block is decoded and thus verified that a bitcoin transaction has actually happened, but then the actual value of a bitcoin would just be fictional and not representing any actuall value.
These are not the only question I have just the ones that are coming right now to my mind, and I will post more after I clarify the ones above.
Thanks a lot in advance.