Hi ,If there is some guid for how I can make our update.zip to upgrate phone.
Are you wanting to make an image to use as a backup?? there's not really a need to make a "update.zip" as you put in your OP and nothing to "upgrate" to as 2.1 isn't released for our device (well there is, for making a custom ROM but if you have to ask how than you don't need to be doing that just yet). Have you rooted the phone yet?
Here's a basic guide to creating your backups.
Full System Backup Using Nandroid | Root Your Droid
You are right to be wary. There is much bullcrap. Be wary of me too, because I may be wrong. Make up your own mind after you evaluate all the evidence and the logic. - Mark Rippetoe
he wants to understand how to build an update.zip out of whatever app/modification he wants to try out... basically the file structure that is needed for the Recovery to recognize the modifications he wants.
edit: i'd like to know this too
Easy ... use the droid_superuser_update.zip as a basis.
Open up in 7-zip. Make whatever changes you need directly in the archive. Push as update.zip to your sdcard. Update as normal. Just tried it myself by installing binaries and apks. Of course these must be unsigned and therefore need the latest recovery image.
I recommend that people use the rom.tgz method instead of the update.zip method. It gives you a lot more flexibility for installing (what to wipe out, the ability to select feature sets, and most-importantly, the ability to select which rom to install from the card, instead of only being able to install "update.zip"). It also gives you the ability to require that it be installed from a particular version of the recovery ROM, AND it can automatically back-up your existing installation before updating. It's a pretty good system.
Take a look at the sholes.info ROM to see the format