First, create an empty text file named 'app.tyl', referred to as app. Now you should open app with Tyl Launcher, referred to as launcher. If Tyl Launcher is not yet defined as the default program to open Tyl files, follow the instructions on installation page to associate Tyl files with Tyl Launcher.

Once opened, launcher runs the program immediately. If the file is empty, nothing will happen and launcher is ready for programming, debugging and running Tyl programs.

All buttons and indicators of launcher are described in Tyl Launcher page, and will be shown here in italized style.

Let's put some code. paste the following code to launcher:
currentdir io.cwd
rootdir string.section currentdir 0 3
projsdirname 'tylprojects'
appbudir rootdir + projsdirname + '\bu\' + appname + '\'
io.write appbudir
appfn appname + '.tyl'
srcpath currendir + appfn
appbupath appbudir + appfn
io.copy srcpath appbupath ?
print 'copied the program to backup file `' + appbupath + '` successfully'
print 'copy to backup failed!'
copied the program to backup file 'C:\tylprojects\bu\app\app.tyl' successfully
This is an automatic backup program, that copies the program to a designated backup directory based on the application name. To ensure that it will work correctly, it is needed to understand program management behavior in launcher.

So, first you have to save the program. Once saved, you run it and you'll see the backup file created in the path that is in the result box. For the program file to be updated by the code in the code box it is needed to be saved.

Now, let's change the code by writing this at the end of the code:
code box moved to edit state and all the code is treated as an edited code that needs to be built. The code will return to its built state just after build or run actions.

It is possible to edit the code in other code editors and use it in launcher. Go to the program file in the File Explorer and open it with a text editor of your choice. Now put edit enabled toggle button in the off state. This will indicate to launcher to get source code from the program file itself instead of the code box, thus enabling code edition in another editor.
Attention: While edit enabled state is off, building or running the program will overwrite the code in the code box, therefore if you have important changes, save them in a backup file!