Yahoo chief executive Marissa Mayer talked up the company’s new focus on content -- and advertising -- at CES on Tuesday, bringing a few media personalities along to help announce several launches meant to simplify and unify users’ online lives.

Mayer took over the troubled company in the summer of 2012, the fifth person to be named Yahoo’s CEO in so many years. In her keynote Tuesday, she said her goal was to turn the company’s Web services into daily habits for users seeking news and other information.

Joining her were a number of new -- and notable -- Yahoo employees expected to play important roles in building Yahoo into a Web video and news powerhouse. First up was journalist Katie Couric, who signed a contract with Yahoo late last year to produce news videos for the company.

Mayer also introduced a new magazine called Yahoo Food, which will have recipes and other culinary news. Yahoo Tech, another magazine, is helmed by former New York Times tech columnist David Pogue, who came onstage to launch the new site.

Some faces from recent Yahoo acquisitions also made appearances. Nick D’alosio, the teenage founder of the news aggregation app Summly, which Yahoo acquired last year, introduced a new Yahoo app built on his service called News Digest. Dave Karp, the founder of Tumblr, showed up to talk about the health of the blogging platform that Yahoo paid $1 billion for in May. Karp said that Tumblr now tops the engagement rankings of the Web analysis firm comScore, and said that the average post on the site is shared online 15 times over.

All of this new content, of course, is ad-supported, and Mayer and the Yahoo team were made sure to mention that the firm is working to make ad buys smoother and simpler than ever. After all, that content push isn’t going to pay for itself.

Mayer closed the show by introducing a performance by musician John Legend. The singer’s rendition of the Beatles classic “Here Comes the Sun” seemed to fit well with Mayer’s optimistic view of Yahoo’s turnaround prospects.