What do you expect of setting up your database or in other words, do you plan as (your self called) "noobs" to develop a order processing system?
Did you check if there might be an "out of the box" solution that will help you with your problem? Might be that there is also some open source that fits your needs.
So you might avoid reeinventing the wheel, especially if you are currently not so sure if you need a whole wheel but later on you might do so but did some architectural mistakes in the beginning making it hard to go on.
Besides this you can also avoid doing some commong software dev. mistakes etc. and you can reduce spending your own ressources on "just" keeping your stuff up and running (consider data security, backups etc.) as the it in this case is just the tool to assist with your work
Never the less when working to gether on the same document / documents you will always have the problem of a conflict when writing to the same data source without messing all things up. So even a database by default will not just help you locking records (like you need to lock your xls) when more than one is trying to edit the same record.
To not end up with nothing just words in this post, here are two links as a result from a quick google for open source order management tools, maybe they might go in your direction. If the are good or not (in all belonging - IT and non IT) I can't tell at all.