force.com platform is like any others software platforms like Java ,oracle ,SAP,etc..,.But it is one of the market leading could platforms works using any supported browsers.
Any body want learn about force.com technologies ,there is very good documentation in
http://wiki.developerforce.com/index.php/Documentation but here you have lot of documentation is there with out anybody guidance it is little bit difficult to navigating the website for experienced programmers also it gives starting trouble.
If you followed some blogs or spoke with somebody who know the platform or watching related videos 5 min that is very easy learning things in the platform.But it is not that much difficult you need to know how to search things following blogs or developer forum help which is properly maintained by force.com developers a very good resource
http://boards.developerforce.com/sforce/?category.id=developers.
Right now you understand how to use sales force resources. Suppose I am learning a new programming i will get lot for question like
1.What is the advantage of this programming language or platform ,how is it is different from other programming languages ,what are the components available in this programming languages how i can use this programming language like lot of questions am stopping this argument here. and explaining how to learn the skills.
Suppose if you want learning developer and admins points of view first you need environment.Here yours question is
how to get force.com environment ?.
Getting force.com environment for development or exploring the platform