Advanced Search
You will find the Advanced Search link to the right of the search box when you are in Catalog [1]. Sample screen illustrates the location of the Advanced Search link.

The Advanced Search window:

In Advanced Search, you can
You may also limit on the opening search screen by
After searching, click on Modify Search to edit your search.
Searching for Multiple Terms
If a word is misspelled, therefore, it is possible you will land on the "no results" page.
Boolean Searching
So the assumption is that a search for:
"Title:data or Title:numeric and Title: Python" means
(Title: data or Title: numeric) and Title: Python
"All Fields: modern AND Title: poesia AND Subject: portugal OR All Fields: brazil" means
(Allfields: modern OR All fields: brazil) AND Title: poesia and Subject: Portugal
The diagram below illustrates the first search above where the red area shows the results of the search:
