Ok bit of a novice so what’s the easiest way to get it in simple terms.
First of all where are you based?
In the US you will have to simply turn on Location and Cortana will take over the search button on your phone, also if you scroll over to your app list and down to C. Otherwise she will prompt you turn on Location when attempting to launch cortana via pinned live tile or via the app list.
However if your outside the US, you will need to sign up to AppStudio to gain access to the developer preview.
Before I give you the links you need to understand that if you enroll onto the preview for developers programme and update to GDR1 / Update 1.
You will not be able to downgrade without using the Nokia recovery tool to reflash, which will completely wipe your device therefore you will lose any unbacked up photos, videos, save game data from games that do not utilise OneDrive for cloud back ups and the same applies to apps.
Also any app that is installed on your phone which has been unpublished from the store. As when you do a restore, apps install directly from the store itself and not the cloud back up.
In the event you go back to 8.1 and cyan via the recovery tool and restore from a back up of the apps & settings made whilst on Update 1 you may encounter issues.
Lastly in the rare cases people have reported of bricking their phones when reverting back to 8.1 & cyan.
However if you are still happy to proceed knowing the risks, the steps are as follows:
1)Back up all your data, photos, videos, documents etc onto a pc or mac (what ever you use via usb, just in case something happens)
2) Go to
Windows App Studio - Microsoft
3) Sign In with your microsoft account tied to your phone & follow the instructions
4) Install the preview for developers from the store
Preview for Developers | Windows Phone Apps+Games Store (United States)
You have two simple methods to install this app, a) search the store b) login into windowsphone.com and click install in the above link, this will push the app to your phone.
5)Once Installed, launch the app and read the terms & conditions.
6)If acceptable, agree and sign in with the same Microsoft account tied to your phone
7)Go to settings, phone update and check for updates.
(I would suggest at this time make sure your phone is fully charged)
8)Once prompted, click download
9)Once the download has finished, click install.
10)The install will take upto 20 minutes or longer depending how much data / apps are on your phone.
11) Once completed the install wizard will migrate your data.
12) If all should go successfully, you will see a prompt showing the update has installed successfully.
13) As mentioned previously you will need to have Location turned on to enable Cortana.
With update 1 you also get live folders, video below:
How to create Live Folders on Windows Phone 8.1 GDR1 - YouTube