I am not new to web building but I started using wordpress for the first time recently and not familiar with its coding. I have a very basic question about it. Lets say I want to insert a poll program that I have or I want to insert a picture or a calendar or any element into a wordpress layout (or should I say theme I am not sure). Is that possible, or once you start using a theme, the layout and everythings is pretty much fixed?
In other words, getting stuck to whatever the theme allows me is not what I want. Can you insert any element that you like at any location and play with the layout? If so can you describe how should I go about it (which folders, where exactly etc... for instance give me an example of doing so in the default theme, where, which folders, which files)?
Note: I am not talking about inserting stuff to posts here. This is about inserting things to the pages.