SimPE Resource Editing
When you starting modding the Sims 2 you will use a tool called SimPE to view and edit the packages you create. There are lots of Internal Formats that SimPE calls resources. You will see the various types of resources in your package shown in the left hand pane of SimPE - the Resource Tree. Each type has a number beside it showing how many resources of that type are in the package you are looking at, and if you select one of the types, the Resource List pane will display a list of those resources. Depending on the type of resource the Plugin View tab will provide a different editor suitable for looking at and editing the resource in question. You will no doubt get to know the resources by their four character names, BCON, BHAV, GMND etc. Each resource also has a hexadecimal number as its type - you will see if it you switch to the Resource tab when you have a resource selected.
[Note: Some screen shots coming and more blurb - this is a work in progress - how do you say that in this Wiki?]