Filling a text field in Safari and saving the page as 'save as'

Question

My telephone system creates a call log and I like to automate downloading it weekly.
In order to get in it needs to enter a password (there is also a user name field but that is left blank by me).
Once in is should safe a ‘Save as” copy to my desktop.
I have written a script and it does not work (probably because I am not good at scripting.
Can anyone help?
This script gets me as far as the dialog box that asks for Password to open.
tell application "Safari"
activate
tell (make new document) to set URL to "http://192.168.1.90"
Thanks

Answer 1

Thank you for all your help above.
Just to confirm your advice, am I right with the following conclusions? :
1. The script (function) to fill the text field with the modification date of a different PDF file needs to be stored in a folder level .js file.
2. The document containing the text field needs to call the .js function either within the document script or within the custom script property of the text field itself.
Further to that can you just advise on the syntax for accessing the modification date of the other document.
Do I need to assign a variable to the address of the file to be used, and then use this variable in the text form filling script (as below) or can I use a direct file reference at the .modDate command.
var LastSync = "C:\sync\bin\lastsync.pdf";
var strMsg = util.printd("h:MM tt",LastSync.modDate) + " on ";
strMsg += util.printd("dddd, d mmmm, yyyy",LastSync.modDate);
this.getField("LastSyncDate").value = strMsg;
If the syntax is totally different to the above I would be very grateful for some guidance in the right direction.
I much appreciate your time to help me ... I'm almost there.
Kind Regards,
Nifty