Let's assume you want to know what is the optimum nursing care of someone with Parkinsons Disease. We're going to use subject headings to do this.

First, break up your question into concepts: Nursing Care and Parkinsons Disease 

In the CINAHL database, type Nursing Care into the search box, and tick the Suggest Subject Terms box above that.

Now press Search, and you will be taken to the CINAHL Subject Headings page:

In this case you can see that the term you chose to search for maps exactly to the CINAHL subject heading, Nursing Care. Tick the box next to that (or you have other choices listed if you prefer). You can then choose to tick Explode (this expands your search to include all the more narrow terms as well as this one - here it would include all specific types or specialties of nursing care) or Major Concept (which narrows your search to only articles where that term is considered a major topic). You then have a list of possible subheadings you can apply. (A good rule of thumb is to start your search fairly broadly and not use those subheadings unless they happen to be exactly what you're looking for.

Here we have chosen to explode the subject heading and choose no sub-headings. Now press Search on the right.

You can see that there are hundreds of thousands of results, because we've found every article indexed in CINAHL about nursing care. Not surprising really as it's primarily a nursing database!

HINT: Always clear the search terms already in the first search box before looking for a new term. Once you start combining terms it will be messy if you forget to do this. Another handy tip is to press Search History under the three search boxes and you can follow your progress.

Now to start searching for your second concept. Tick Suggest Subject Terms, and type Parkinsons Disease into the search box and click Search.

Again, you'll arrive at the CINAHL subject headings page:

Now you can start to see how useful it is to use subject headings. If we had been using keywords, we would have had to search for Parkinson OR Parkinsons OR Parkinson's (or you could have searched Parkinson*). Now we know that all the articles about this disease are indexed under this one term. You can see that Explode is greyed out, and that's because there are no more narrow terms for this. We've decided to make this a Major Concept this time, because we really want the articles to be primarily about this disease, and not just mentioned.  If you need a definition of any of the subject headings, click on the little yellow note next to the Major Concept box for a description. Now press Search.

It's time to combine our concepts. Scroll down under the search boxes to your search history, tick both terms and click Search with AND:

Now there's a much more reasonable number of results, which you can filter down the left hand side using Refine Results, or alternatively, click the Edit button next to the number of results in your final combination.

Look at the HTML and PDF links to access the full text of the article. Hint: If you cannot find a link to the full text of an article it is most likely in another database and can be found with just a couple more clicks by following the Find it at CSU link.