How to schedule a backup of SQL Server Transaction Logs and Databases.
I've been doing this for a few years since running our servers in-house. If this is not performed regularly with both a Transaction Backup and Database Backup, you will run into significant issues, like your Log Files filling up and growing HUGE; when I say huge, I mean, Gigs in size. The most extensive our Log file ever grew was over 20 Gigs.
Doing the following two Backups is crucial when running a Live SQL Server in a Production Environment, especially if you are running an [Always On High Availability Group] or [Always On]

1. [Step 1]
   From your Windows [Domain Controller].
   Open [Active Directory Users and Computers]
   Expand the [Domain.Local]
   Click on [Users]
   Right-click on the [Users] folder
   Choose [New], then [User]
   When the [New object - User] window opens.
   Fill this page out.
   Give the [Username]: sqlagent
   click [Next >]
   Give a good password. (I choose User cannot change Password & Password never expires)
   Click [Next >]
   Then click [Finish].
   Double-click on the new SQLAgent User.
   Click on [Member Of].
   Click [Add] and copy and paste the following names in the window.
   Administrators;Domain Admins;Domain Computers;Domain Users;Server Operators
   Click on [Apply] then [OK]. Next
   Right-click on the sqlagent and choose [Copy]
   Give the [Username]:
   Fill out the rest of the information.
   Click [Next >]
   Type in a [password].
   Click [OK].
2. [Step 2]
   Add both users to SQL Server Logins.
   Click on ServerName\InstanceName
   Click on [Security]
   Click to expand [Logins].
   Right-click on Logins
   Choose [New Login]
   Give Login Name: DomainName\sqlagent
   Click on [Windows Authentication]
   Click on [Server Roles] from the Left-panel.
   Check the following [Server roles].
   dbcreator
   public (default checked)
   serveradmin
   sysadmin
   Next, click on [User Mapping]
   Click on Master from the top panel (User mapped to this login).
   You will see the new User we added selected as User.
   Under [Default Schema] type dbo
   Click [OK]
   Repeat for the other User.
3. [Step 3]
   You must give permissions for the sqlengine and sqlagent to control the SQL Services.
   Open [Control Panel]
   Then [Administration Tools]
   Scroll down to [SQL Server Agent]
   [Right-click] and choose [Properties] (or) [Double-click] to open [Properties Window].
   From [Startup Type:] Automatic
   Click on [Start]
   Click on the [Log On] tab.
   Type in the following for the login.
   This account: domainname\sqlengine
   Password
   Confirm password:
   Click [OK]
   [Next]
   Double-click on [SQL Server (SQLInstanceName)]
   Perform what we did for SQLAgent.
   From [Startup Type:] Automatic
   Click on [Start]
   Click on the [Log On] tab.
   This account: domainname\sqlagent
   Password
   Confirm password:
   Click [OK]
   
4. [Step 4]
   Next, we need to give access to the folder for both our SQLEngine and SQLAgent
   (This part of for those who are running Windows Core Servers)
   Using [Computer Management]
   Right-click on [Computer Management]
   Choose [Connect to another computer...]
   [Another computer]: ServerName
   Expand [System Tools]
   Then expand [Shared Folders]
   Right-click in the Shared Folders window and choose [New Share]
   Click [Next >]
   Click Browse:
   [Create New Folder] for G:\SQLServer\Backup
   [Next >]
   Choose [Customize permissions] click [Custom...]
   Choose [Add...]
   Type in both users separated by a semi-colon.
   Authenticated Users (You can also add an admin user here as well for monitoring the folder(s))
   Give [Full Control] to/All users.
   Click [OK]
   Click [Finish]
   Click [Finish]
5. [Step 5]
   We have to enable [xp_cmdshell] to allow SQL Server to perform a backup.
   Open a [New Query ] window. Copy and Paste the following code, and run it.
   EXEC sp_configure 'show advanced options', '1' RECONFIGURE -- this enables xp_cmdshell EXEC sp_configure 'xp_cmdshell', '1' RECONFIGURE
6. [Step 6]
   From SQL Server, Right-click on [SQLListener,2433] (Or your SQL Server Name) [ServerName\InstanceName]
   Choose [Facets]
   From the [Facet] list, choose [Server Security]
   Make sure [XPCmdShellEnabled] = [True]
   Click [OK]
   
7. [Step 7]
   Open SQL Server Management Studio (SSMS for short)
   Open [SQLListener,2433] (Or your SQL Server Name) [ServerName\InstanceName]
   Right-click on your database and choose [Properties]
   Choose [Options] from the Left-panel.
   Change [Recovery model]: to [Full]. Click [OK]
   
8. [Step 8]
   Scroll down to [SQL Server Agent]
   Right-click and choose [Start] (If it is already started, leave it alone.)
9. Next Step. Follow the two Related links below to schedule backups for your Trans and Databases.