If you have a Windows laptop, it comes with a native text editor named Notepad. Notepad, however, is a tad limited.
A better choice is to download Notepad ++.
It is both useful and free.
Macs come with a native text editor named TextEdit. It, however, tries to add tags to the tags you will write and that will mess up your web pages.
Follow these instructions to change the default preferences so it will work for you as an HTML editor.
Either Windows or Mac OS
However, you might want to try Brackets.
It, too, is both useful and free. See which one fits your working style better and stick with the one you select.