You will need an OHDSI wiki account and then you can log into the wiki with the login link at the top right of the wiki page. Once you are logged in you can edit wiki pages.
Due to aggressive spammers, OHDSI wiki account self registration is not enabled but you can message me here at @admin with the following info and I can create the OHDSI wiki account for you.
user id - whatever you want it to be
user first and last name
email address - must be a valid email address