Try something like jslint.com
You paste in your script and it will be really hard and nasty on you and find syntax and basic logic flaws. Once all that is good, you can start looking at the logic.
As to the Script tab, did you mean your custom script was actually named "jquery.js"? You could copy paste your script into here and we could look at it. If you're new to jquery, Firebug might not be right avenue to take right now.
One thing I've learned is to put alerts in the script at certain times to make sure values and such are what you are thinking they should be. So if you have a function when a user clicks on some work or element, put an alert.. alert("they clicked"); as the first line in that function to make sure the function is getting called. For instance.
If you can paste it here, someone might be able to help out.