1. To search you can type your phrase into the search box: for example, perforated appendicitis. It will search in all fields and also break the phrase apart. If you get too many hits, then you can put quotes around the phrase: "perforated appendicitis" --be aware that this will only search for the phrase if it is in the index and will not search the MESH field. If the phrase is not in the index, then it will break the phrase apart and search the words separately in all the fields and as a MESH term. For example "dark chocolate" does this: dark[All Fields] AND ("cacao"[MeSH Terms] OR "cacao"[All Fields] OR "chocolate"[All Fields])
2. perforated AND appendicitis --will search for the two words in all fields but not necessarily next to each other.
3. perforated appendicitis[ti] --searches for the two words in the title field. This is a good way to start your search in order to find articles quickly that are primarily about your subject.