Install Android 2.3 Gingerbread Cyanogen Mod 7 on HTC Wildfire
First of all, confirm that you have a rooted HTC Wildfire. If you don't, root it before you proceed further. You can do that here by following these directions.
Next, download the Android 2.3 Gingerbread Cyanogen Mod 7 ROM for the HTC Wildfire. It's a nightly build so it may have a few bugs.
It doesn't have Google Apps installed, so you should also Download Gapps if you want them.
Copy both the Android 2.3 ROM and the Gapps files to the root of your SD card.
Search for ROM Manager on the Android Market and install it. Launch ROM Manager and select the Flash Clockwork Mod Recovery option. Install a recovery image and create a backup of your existing ROM if you want.
In ROM Manager, click on the Install ROM from SD Card and select the Android 2.3 Gingerbread Cyanogen Mod 7 ROM you copied to the SD card.
Select both the options - Backup existing ROM and Wipe Data and Cache before installing the ROM. Your phone should reboot into the recovery mode and ROM flashing should be complete.
Once it is done, also flash the Google Apps ZIP (for all the native Google apps found on Android) from ROM Manager. Your HTC Wildfire should now be running Android 2.3 Gingerbread CM7.
Note: Flashing ROMs is a risky procedure. Continue at your own risk. There aren't any known bugs in the Cyanogen Mod 7 Android 2.3 ROM, but you can't be sure until the final ROM is launched. You could wait for the final ROM, but the nightly ROM is quite stable too. If you have any doubts or queries, check out the official XDA thread posted below or leave a comment.