Don't be scared ssarah - I am a retired team mgr of a fostering & adoption team - retired in 2004 so bit rusty and we didn't use an online workbook. Look the abosolute main thing is that you are a good foster carer who will always put the child's needs first. Online stuff is far far less important, and get your link worker to help or the child's sw. Why not get together with other foster carers in your area (many of whom are probably feeling just like you) - do you meet informally? Where I worked the foster carers met formally (with a chair person, treasurer etc) and informally at coffee mornings in each others houses. If there are a few of you unsure about this online stuff make it known together to the SSD and ask them to put on a training session (of course they probably don't know how to use it themselves!)
You can obviously work online and I assume the workbook is a template of some kind that you complete.....if you want to PM me and give me a bit more detail of this workbook I can probably point you in the right direction, but sws should not just expect fcs to know how to do these things. It probably won't even be looked at - it is probably a tick box thing on the huge amount of stuff sws have to tick as completed.
When I was working for a LA something called the Common Assessment Framework was used for recruiting and assessing (It might have died now!) and as part of the process prospective foster carers had to complete a "portfolio" and they were mostly worried about this, but sws in my team helped them. Many prospective foster carers completed long portfolios, with photographs and to sort of give an idea of who was who in the family and their parenting skills etc. Incidentally portfolio is another word for a folder!! Maybe you had to do something similar during your assessment?
Anyway these portfolios were quickly passed around the Fostering Panel members who were always running late (and no one had time to look at them) I mentioned this to my manager and asked what happened to these portfolios and she said she wasn't sure! Well the answer was they just gathered dust in file or on a shelf.
Enjoy caring for your LO and stop worrying about workbooks - that's an order ok??