EasyGPS is a great program to help you download waypoints into your gps. I use it quite a bit with my Meridian Plat. Also, you are right for inputting waypoints manually, hold down Goto for 2 seconds, enter in all of the information (coords, cache name, icon if you want, etc...) and hit save. If you go to the map screen, it should be on there (you may have to move the cursor to it or zoom out if it is far away). Then when you are ready to find the cache, hit GOTO, highlight User (since you are the one who put in the coordinates) and then on the bottom of the screen you see Find By. You can choose alphabetical, near position, or near city (since most of the cache's I've found so far have just been a few miles away, I use near position). The next screen will be a list of waypoints that are available. Find the name of the waypoint you created for the cache, and hit enter. Now on the map screen there will be a straight line from your current position al the way to the waypoint of the cache. Hope this helps and doesn't confuse you even more!!
Wes