MS Access Problem - Dependant fields on a form

ok, i'm a total newbie to ms access. Basically, what I need is when I input some data on a form, I need some other data to be assumed, from other tables.

So when I select "1" for example in a field, I need that to be linked to another table, and therefore rule out certain possibilities. So if the field is "1" then another field cannot have the word "access" in it, just for example. Is there anyway to do this?

Any help would be appreciated. By the way, is anyone else having problemse seeing their writing when they write the message? I can't see what i'm typing while I type here... So i apologise for any spelling smistakes.