Its okay to be overwhelmed. Start loading crap onto your phone based on what you want to do. Be sure you get a good backup program first like pim backup. Anything you see referenced here you can copy and paste into your google search and it will most likely take you back here to the proper posts or to another similar site xda. these two sites can be trusted and will keep you busy for months.
back up your contacts and appointments before you start playing with your phone and quite often when you start to load stuff. then load crap on try it out and uninstall or use it. eventually you will probably get to the point where you need to reset your phone and start over.
unless your good at computers dont change your oem rom (the operating system that came with your phone) yet. get some add on software and play with that for a while.
get oem aps on posts like this one:
http://forum.ppcgeeks.com/showthread...ight=oem+touch
take the files onto your phone and load them from your phone. "cabs" load by themselves, zips and rars need to be unzipped and then may have a cab inside or you gotta play around with them. usually there is a "read me" file that explains it.
Also trick out your phone. I would start with slide to unlock (do a search to find it) and spb mobile shell. That stuff will entertain you for awile.
one last thing you gotta do is push the green "thanks" below my post. my rep aint budging.