As you become more experienced with HTML, you may want to create more files with your own HTML editor and transfer them to Yahoo! via the Easy Upload utility (GeoCities Plus and Pro users can also use FTP to transfer their files). The advantage of a local editor over the Yahoo! HTML Editor is that a good local editor will automatically insert many common tags for you, saving you time.
For more information on creating tags, using HTML, and working with other HTML editors, try these resources: