If your topic is something that needs more than a general database such as Academic Search Ultimate or Google Scholar can give you, it is best to use a subject specific database. These databases focus on specific topics and will have more journals devoted to their topics, giving you more information than you would get from a general database, that has a little bit on every topic.
To get to the subject specific databases, you start from the Library's Homepage to get to the A-Z list of Databases, just like you would to get to Academic Search Ultimate. The difference is that you want limit to a specific subject from the All Subjects list. This will give you the options of databases that are focused on your subject.
The example to the right is the list of Nursing databases, chosen from the list of subjects.
You might notice that Academic Search Ultimate is still one of the options, because it does cover this topic a bit. It will usually give it's best guess as to which databases would be the most helpful, if you do have a specifically nursing topic. However, if you chose the subject of nursing since it was the closes to your general health science question, those best bests might not be the best for you.
There will usually be a subject guide on the left side, where the librarian over the subject has put together tips and tools to help your research within the subject easier. It's a good idea to check those out.
Using a subject specific database is no different then using a general one. The biggest difference will be how many results you will get within that subject. Most of the SUU databases will be EBSCO, and so will look EXACTLY like Academic Search Ultimate. Others will look different, but will have the same basic features: a search bar, Boolean operators, and limiter options.
The searching and limiter options might be called different things, but once you start using them, it is generally easy to find the equivalent features and to use them in the same way.