The major part of software on a Mac resides in the icon in the Applications folder (if you control click or right click) on an Application icon you'll see "Show Package Contents". So Mac applications are self contained. so just dragging the application to trash will do.
However, there is a more through way. Just do a search on the Application you want to remove, then just drag the files from the search window to trash. Warning though, if you throw away Apple applications (i.e Quicktime, etc.) can cause some havoc with your system.
If you really want to get a real good basic understanding of OS X I would strongly suggest
David Pogue's Mac OS X: The Missing Manual, Panther Edition. Plus, there is a couple easy steps to keeping OS X it tip top shape. They are not a guarantee to stop all application crashes, but they will help prevent a lot of future headaches.
1. Once a week and after every big software install (Apple updates or big program installs). Run Application->Utilties->Disk Utility and then highlight you startup drive then click "Repair Permissions". OS X is based on BSD Unix and unix loves permissions. Each software company installs like to screw with the OS X file permissions so Repairing Permissions with Disk Utility will set the file permissions correctly.
2. Stay far away from a old Disk Utility that has been
discontinued. That companies product has a history of crashing many OS X systems. Just search this board and many others to see that.
3. A great OS X disk utility is IMHO
Alsoft's DiskWarrior. Also, another companies disk utility called
TechTool Pro gets high marks too.
4. A good site to see about hardware updates is call
xlr8yourmac. If any has been done to a macintosh then the site has some soul who tried once and written about it. The site also has very good databases for searching for part compatibility.
5. A great ram buying site is
ramseeker.
These are just a small sampling of hints. The book I pointed out will have many more. I would strongly suggest in buying the book. Good luck.