The dictionary defines tablature (or tab) as "a form of musical notation indicating instrument fingering rather than musical pitches." Basically a simplified method of reading music, it is extremely popular with guitar players. Classical sheet music can be converted to tablature by hand or by using computer software. There are also online resources with classical pieces already written in tab format.
Begin by using some simple reference material such as a scale pattern written in standard music notation. Identify the notes and look at where you play them on the guitar. Transfer them one at a time to tablature notation, using the six lines on the page to represent the six strings (low E string to high E) on the guitar and the numbers to represent the fret where you finger each note. Use websites such as Class Tab for pointers when writing the tablature.
To convert classical sheet music to tablature, transfer each note into tablature format one at a time. Write down only the fret numbers of each note. Unlike standard music notation, there are no note rhythmic values, only the fret numbers that represent the pitch of each note. Chords are written as a column of numbers whereas single notes are written as separate numbers. Use a website such as Music Effect to help you understand "which line represents which string and which note."
Buy a book from a retailer such as Amazon that shows classical pieces in both standard notation and tablature format. Work through all the songs, first reading the standard notation and then the tablature. Convert standard notation to tablature on your own from a piece of sheet music. Use the book to help you understand the similarities and differences between the two notation methods.
Use an online resource such as Class Tab with over 950 classical pieces converted to tablature. On the homepage scroll down to the list of classical pieces and click on one to view the tablature. Use the alphabetical search to click on the first letter of the classical piece you are looking for. Print the tablature from the website.
Use specific computer software for standard notation to tablature conversion, such as Finale Print Music. The program allows you to drag music from a standard notation staff line into a tab stave below and is designed for musicians that wish to use both tablature and standard notation. Click on the "Try It" option on the Finale Print Music website (located on the lower right corner of the page) to download a free trial version to test before buying the full version.
On a guitar (or bass) there are many ways to play the same notes, so be aware of fingering positions.