Google Scholar can be searched using keywords, just as you would use in any Google web search.
You can find many more search tips at scholar.google.com. Click the "Help" link at the bottom of the page.
A publication-restricted search only returns results with specific words from a specific publication.
For example:
If you want to search the Journal of Finance for articles about mutual funds, you might start like this:
Keep in mind, however, that publication-restricted searches may be incomplete. Google Scholar gathers bibliographical data from many sources, including automatically extracting it from text and citations. This information may be incomplete or even incorrect; many preprints, for instance, don't say where (or even whether) the article was ultimately published.
In general, publication-restricted searches are effective if you already know what you're looking for.
Finally, bear in mind that one journal can be spelled several ways (e.g., Journal of Biological Chemistry is often abbreviated as J Biol Chem), so you may need to try several spellings of a given publication in order to get complete search results.