Request help regarding development of an add-on for web browsing

Mohsen Mashhour

my name is mohsen and i am visually impaired, suffering from albinism.
i develop an add-on for browsing web. in that i need to call some functions to jump to the next or previous part of a web page without pressing a key on keyboard. for example in this add on i have a gui with two keys to go to next or previous headings in current webpage.
what module or classes should i import and how to call the functions to jump to next or previous item (for example headings, links and ...)

best regards