vang,
I've searched for tutorials on this nature, and you will have a hard time finding it.
Generally beginners tutorials, etc are not geared towards such a direct business usage, many businesses will just pay for an existing system, or a software development firm will develop it either custom, or for resale.
What I recommend you search for is PHP+MySQL Tutorials
That is generally the method you would use, inventory is generally more than 1 table, as you have to contend with warehouse & stock locations (usually denoted by an ID, which in another table gives you the human readable form)
This doesn't mean that this is the way you must do it, it is just how at least the ERP systems that I have used work.
Book keeping is a little above my head since I am not a finance guy, however I would imagine that would use a few tables in itself, for bank accounts, currencies, trasactions (its own table), transaction types, etc.
I can also recommend that you draw out on paper, or use a Mind Mapper (such as FreeMind, which I use) to sketch out a visual representation of every field you plan on using.
Along with the PHP+MySQL tutorials (plural) you should be able to get started.
If you're already well familiar enough with MySQL, search for an Open Source ERP system book / documentation, that will give you an idea of the table structure they use for both financials & inventory.
I hope this was of some help.
