Since you are a new user I will help you with a little more depth, I hate seeing new users mess up their device. Give me a second to get it together and I will edit this post with some helpful info.
OK so Follow the instructions on this page ( http://forum.xda-developers.com/show....php?t=2416431
) to get a custom recovery. It's TWRP, and I like it a lot. I love that it's touch, because I remember using amon ra on the HTC Evo and you had to use the volume up & down + power button to navigate the menus and it was sometimes very easy to make a mistake. This touch recovery eliminates that.
Next, go to either the original android development OR the android development section of the Verizon HTC One and choose either an AOSP rom or sense based rom. So far I've used the Google Play Edition rom and now I'm on andy's bonestock and have really liked them both. Make sure any rom you ever flash is compatible with your phone, very, very important. if you don't know, just ask. MOST users on here are friendly and will say yes or no and not give you a hard time.
Roms are very easy to install. Just download the .zip, I download it straight from my phone, but you can also download on your computer and then transfer it to your phones storage. (thanks to andybones advice, I have started checking the MD5 of the rom. Devs include it in thread of the info of the rom here on xda, and once you have the .zip on your phone, use a file manager to view the MD5 and compare it to what the dev has put in their thread. If it matches, you're good.
Then boot into recovery and DO A BACKUP OF YOUR STOCK AND KEEP IT!!
Everything you need to backup is already checked with TWRP so that's helpful. Once you're done with the backup, then do a wipe. I wipe SYSTEM, DATA, CACHE, & DALVIK CACHE.
Then, go back to the TWRP main screen and select install. Find the .zip you want to install and flash it. Some roms have aroma installer so it will bring you to a special screen that allows you to select options you want to have in the rom. check the boxes of the apps/options you want in the rom and follow the 'next' prompts until the rom installs. After you're done, reboot, set up your new rom and enjoy it!
If anyone more experienced than me has any info to add to this, feel free.
Have had way too many phones to list. Currently HTC One on Verizon Wireless.
I like Apple & Android equally. Shocker, I know.