A common phrase you've probably seen thrown around as though you're supposed to know what it means is "flash a zip." Someone will create/post a great hack or app on a forum and just tell you to flash it on your EVO. Simple as that . . . but how are you supposed to do it?
A .zip file obviously isn't an .apk, so you can't use a file manager like ASTRO or appInstaller. Putting the .zip on your SD card doesn't do anything by itself, the question you posted in a forum never got answered, and Google isn't very helpful either.
But don't give up. Flashing a .zip may sound foreign and complicated, especially if you've only ever unzipped a .zip on a computer, but it's actually very simple.
Before we get started, install Quick Boot on your EVO.
It's one of G&E's top 10 root apps for the EVO and gives you one-tap access to recovery mode, which is where you flash the .zip.
Now let's continue.
Note: It's always good practice to do a Nandroid backup in case something goes wrong and you need to go back to before the .zip was flashed.
1. Put the .zip you want to flash on your EVO's SD card. We're not talking about an update.zip here, so you don't have to rename it or put it in a specific place.
2. Boot into recovery mode (here's where Quick Boot comes in handy). I'm just going to assume you're using the ClockworkMod custom recovery; if you're not, the steps might be a little different, but the process should be the same.
3. Use the EVO's volume down button to navigate to "install zip from sdcard" and press the power button to select it.
4. Select "choose zip from sdcard" using the volume down and power buttons.
5. Navigate to the file you want using the volume down button (if you put the .zip in a folder, press the power button to open the folder; you need to select the actual .zip file, not the folder it's in) and press the power button to select it.
6. Confirm that you want to install the .zip (this can't be undone) by selecting the "Yes – Install [name].zip" option that's sandwiched between a bunch of "No" options. No chance of accidentally pressing "yes" like this!
7. When the installation is complete, select "Go Back" and then "reboot system now" (again using the volume down and power buttons).
Congratulations! You've just flashed a .zip on your HTC EVO. You can flash custom ROMs with this method too (do a Nandroid backup, clear the cache, and wipe data first), but the process is easier and more streamlined using ROM Manager, one of G&E's top 10 root apps.