Salesforce has a great video guide to help new users navigate the interface. It goes over all of the object types, how they are used and where to access them. It is more of a fancy power point presentation than a video but that's OK. It makes it very easy to follow along on your dev org as you watch each step.
Go to https://help.salesforce.com/
On the box labeled Training you will find a list of video links.
Choose the one labeled "Getting Started: Navigating Salesforce"
I would watch this one a couple of times while following along on your dev org. What they go over are the building blocks that all of Salesforce is based off of. The main thing you want to walk away with from this video is the terminology that is used to describe each object and what each object's roll is.