Rojo,
Unless you have hidden it, your 899 unit should show you the Snapshot and Recording View when you scroll through all of the available Views. Go to this View and press the MENU button once. You should see the Start Recording menu. Activate It by using the Right Arrow button. You will need a memory card in your unit to be able to do this. Once the recording is started you can view any pf the sonar or GPS Views. When you want to stop the recording it should be the first menu listed on all of the Views.