Flashing a ROM is overwriting the system file with a new one.
Ok, you are already on 2.3.340. That's the Droid X Froyo ROM. To get to Gingerbread, which is Android 2.3, or 4.5.596 ROM, you root using Z4, download the 2 part TBH files, and install Droid 2 bootstrap (hit bootstrap recovery when its installed, it will say success, then hit reboot recovery). This will boot you into Clockwork recovery. Use the volume buttons to highlight data wipe, and the camera button to select. Then go to advanced and choose wipe dalvik cache. This will give you a clean slate to install the Gingerbread ROM. Next, select install zip from SD card, then choose zip. Find the 2 part files you downloaded and install them IN ORDER! If you don't, you can brick your phone and you will have to sbf and start all over.
After you install the 2 part files, you can use the back button to get to the main screen of Clockwork Recovery, and select reboot. You are now on rooted Gingerbread. If you decide you may want to go back to the stock GB ROM from Apex, create a backup in Clockwork by selecting backup and restore, then backup.
If you want Apex, after you are done installing the 2 part Gingerbread files, find the Apex file on your SD Card, and install it. Then reboot. Your first boot might take a couple minutes. As long as you have wiped data, you shouldn't worry about it.
Here is the link to Apex:
http://www.droidforums.net/forum/fabolous-x/152337-rom-apex-v2-0-0-release-candidate-rc2-6-11-2011-a.html
Make sure you download the 2 part Gingerbread files, and Apex before you go into Clockwork recovery. That way you don't have to exit or anything to download. You can just flash and go.
Make sure your battery is atleast 70% before you do this. It will not charge while you are in Clockwork Recovery.
CM74DX
welll i guess i mis-read the directions. when in the boot menu thing, i skipped the wipe data, first i wiped the dalvik cache, then because i didnt know which tbh file was which i just rebooted. and then i went back and read directions and saw i needed to wipe data so i did that, and then i wiped dalvik cache again and rebooted. and right now my phone is displaying the lil android guy with a warning sign, the triangle with the ! inside.. been like that for several minutes.
so what should i do now??? take out the battery? did i brick my phone already? lol