Something related to orthography — the conventional spellings of a language — can be described as orthographic. Orthographic comes from the Greek roots ortho, meaning correct, and graphos, meaning writing.
You have made several orthographic errors if you write "alot of peeple came two the skool." The spelling of "a lot," "people," "to," and "school" are all incorrect. If you tend to spell this way, it's possible that you have an orthographic processing problem, or trouble visualizing the correct patterns for spelling words, which can also affect how well you can read. English has so many odd spellings that almost everyone makes the occasional orthographic mistake.