I understand the instructions, but there are two difficulties. The first is that iTunes has default settings which you need to override before connecting an external device, as they're implemented automatically and their significance to a new user is far from obvious.
The second is that "sync" has a number of different and mutually exclusive meanings - it is not a closely defined word. The best description of this that I've seen is within the Windows package Beyond Compare, where they explain the significance of each option and allow the user to make an informed choice. Some of the major options are:-
1) make both sides identical by adding files found on one side but not the other; delete nothing
2) write into side 2 anything found in side 1 and not already present; delete nothing
3) delete files found in side 2 not found in side 1
4) treat different generations of the same file as distinct files to be dealt with as above
5) treat different generations of the same file as options, and overwrite other versions with the desired version (as specified in parameters)
There are several more choices. The effect of each of these is profoundly different from the effect of the other choices, and extreme care needs to be taken to avoid unintended loss of data.
My difficulty is that I can't tell what Apple mean by "sync", and if I guess wrongly I shall irrevocably lose data - as happened to me recently. What I want done is for the iPad to have added to it files I select on the computer, with later versions overwriting earlier versions, and nothing deleted from either side. What happened to me was that the iPad was first stripped of data, which I then found was irreversible. I was also surprised and annoyed that I was working in Videos only, so rather assumed that any decisions I made would affect just videos. Not so - all music on the iPad was deleted even though I had no intent to do that.
The various definitions I've been given of Apple's "sync" are different from each other, and so far as I can tell none corresponds to what actually happens. So so far as I am concerned and until I learn otherwise, "sync" is dangerous software that I want nothing to do with, and much the same goes for iTunes in general. The data on the iPad is stored in directories just as on OSX and Windows - why can't they simply allow you direct access to those directories as with those other systems? Why do they force people to use this package iTunes? The iPad would perhaps be greatly improved by a third-party OS that changed these things to operate according to industry norms.
I meant to add. The dictionary meaning of "synchronise" is (roughly) "to make equal" - to change both sides so that they become the same (without specifying precisely how). That is patently inappropriate to updating portable devices from computers, as they have so much less storage. So right from the start they've chosen the wrong word. Now many people these days are happy to accept whatever jargon use of words is presented to them (witness "status" in Facebook). Other people still try to relate new uses of words to their generally accepted meanings, and I confess to being one of those people.