You enter the basic search string in [1]. Optionally, you can enter "COLLOCATES" words in [2], and indicate how many words away this is with [3] and [4]. You can use the "Part of Speech" list in [5] to enter tags into [1] or into [2] (when [2] is visible). You can toggle whether to use [COLLOCATES] and [POS LIST] by clicking on these words.

You would use just [1] when you have an exact number of words that you're searching. For example, buy [nn*] in [1] would find a two word string, composed of the word buy immediately followed by a noun (click to try it).

With the COLLOCATES / CONTEXT searches, on the other hand, the word in [2] can occur anywhere "near" [1], as specified by [3]-[4]. For example, click here to find all cases of a noun within three words to the right of buy.