Go to your desktop and right click on an empty space choose New then Text Document.
After opening the file, copy the code below and paste into the file.
<title>This is the title</title>
<center>My first web page!</center>
This is everything that goes in the document!
It's time to save the file so go to File > Save As after clicking on save as you need to keep few things in your mind.
a) After naming (what ever name you want) the file make sure you write .html
b) File type should be All Files
c) Last thing you should choose Encoding as ANSI then click save.
That's it you've made your first web page with Notepad.
Edit a program file.
It is very simple, to edit a program file right click the file you want to edit then choose Open with then Notepad as you can see the picture at the top of this page.
Remember which ever file you edit don't delete the file name from the dot for example .php, .html, .dll, and .h or what ever name you see and another thing is that backup the file before you edit it because if you make any mistake in the coding you can always replace with the backup ones.
I hope this will help you in lot of places. Thanks