To write down a tablature you will have to use VexTab a specific language that doesn’t seem too hard to learn (see the VexTab tutorial). The edition box is used to enter the notes to be (dis)played (numbers as in normal tabs) associated with the number of the string. Then you can display playing techniques like bending or vibrato by associating the note with a code letter i.e. b for bending or v for vibrato.
I like the final rendition of these tablatures, and I think that VexFlow could really ease the tabs edition process for many editors of guitar lessons blogs, and websites as it skips the use of any external software (it runs in the browser), and you will be done managing lot of pictures. If you want to know more about VexFlow you should check vexflow.com via @clementdelmas.