Since you are using SQL Server Express, you will have to get creative. You don't have any SQL Server native scheduling tool, you can utilize Task Scheduler, and schedule a daily task to run SQLCMD, with query text to backup your database.
I'd recommend creating a script that does some string manipulation to generate a day-unique filename for the BACKUP DATABASE T-SQL.
Your script could resemble something like this:
-- declare the backup filename (with path) without the file extension
declare @DestFile varchar(128) = 'C:\BackupDir\BackupFileName_';
-- get the current date as a nice and sortable string
declare @CurrentDate varchar(64) = '';
set @CurrentDate = replace(convert(varchar(10), getdate(), 111), '/', '');
set @DestFile += @CurrentDate + '.bak';
backup database YourDatabaseName
to disk = @DestFile;
go
Save that T-SQL to a script file (for example's sake, C:\YourScriptDir\BackupDatabase.sql). To run this script using SQLCMD, you could do:
sqlcmd -S YourServerName\YourInstanceName -i C:\YourScriptDir\BackupDatabase.sql
Then just schedule that with Task Scheduler to run daily. It's one giant spaghetti workaround, but that's what you get with a free version.
(the above process would be tailored to a database in Simple Recovery mode. If you are in Full, then you need to consider transaction log backups as well)
