It's free to download in the App Store and Google Play under the name FreshFlow. Once you have it, log in using the same credentials as for the FreshFlow web app.
Click the phone icon for that contact and make the call.
You'll get the option to pick what kind of call it was (like acquisition, care/service etc.), and then you'll also be able to assign a result from a set of predefined possible outcomes for the call.
If you agreed with the client on a follow-up activity (like a meeting, task etc.), you can log the planned activity right away.
Just pick which activity it is, choose the time, and if needed, add a note.
After saving, your call—along with the outcome and any follow-up activity—will be saved as an activity both in the calendar and on the contact card, and potentially also in the task list if the follow-up activity is a task.