Sorry to hear that you need to undertake a job search. It's stressful, but you can do this.
If you're not sure how to start with using this app, just hit the "+ Add" button above, and play around with it. Enter the name of the employer to which you are applying and the title of the job. That's all.
If you'd like to record more information, hit the "..." button, and you will be able to add any amount of other data about the application, like pay range, a URL for the posting, contact information, the state of the application. Anything, really.
Questions? You can contact the developer of this app at adam[dot]crossland[at]gmail[dot]com.