You can find this in either the Candidate list from the side menu or in the Vacancy record Search Tab (candidate list sub tab).
If you don’t see the Boolean search the click then search settings button (spanner and cog icon) and select it.

A new feature added to the search options in Applicantextra’s candidate list is the ability to search for words or phrases across CVs and/or records using AND, OR and NOT statements, known as Boolean logic. You can also group collections of searches together with brackets and also specify phrases with speech marks. So for instance if you wanted to look for candidates that had either Marketing or Sales in their records you type Marketing or Sales in the box and click the cog icon and select Search records only from the menu. If you wanted to extend that search so that who ever had either of those words also had retail in their record the you could group the first statement with a bracket and then AND it to the word retail, like this
(Marketing OR Sales) AND Retail

If you are looking for multiword phrases like Marketing Consultant or Sales Representative then be sure to surround those phrases with speech marks otherwise they will be considered to be Marketing OR Consultant, so in this case if we want to find a candidate with one of those two phrases and Retail we would do this…
(“Marketing Consultant” OR “Sales Representative”) AND Retail

Also you can specify words and phrases that would exclude a record from this search using the NOT command. So if we extend the previous example to exclude anyone who has the word Obnoxious in their record it would look like this…
(“Marketing Consultant” OR “Sales Representative”) AND Retail AND NOT Obnoxious

and then if you also wanted to exclude a choice of words or phrases you could group them with brackets and use the OR statement….
(“Marketing Consultant” OR “Sales Representative”) AND Retail AND NOT (Obnoxious OR “Really Annoying”) . Be careful with using AND within a NOT bracket, this will effectively only exclude records that have all of the listed criteria, in most cases OR will be what you need to exclude records with any combination of the listed criteria.

There is also a wildcard function that allows you to look for partial words like Derby* would look for similar words with any number of characters after the word you specify like Derby or Derbyshire.  You can use them on the front back or middle so, *shire would match Oxfordshire, Derbyshire, Cambridgeshire and *erl* might match Sunderland and Sutherland . There is a single character version, so ?ooked would match to cooked, hooked or looked but not to spooked or brooked because its more than one character different.

That about covers everything except to say that this box by default will search across both records and private CVs but by clicking the cog icon to the right of the box you can toggle it to search one or the other as well.
A final note on record search modes, these will look in the following locations….
Candidate name
Skills (and any aliases of Skills)
Qualifications (and any aliases of Qualifications)
Roles (and any aliases of Roles)

with feedback we may look at extending this and possibly allow users to narrow down the searching to individual areas so keep in touch.