Welcome to Bike Forums Kunoichi !
Apprehension is very common to starting to ride; that feeling will come, but don;t let it dominate you.
As noted by Martianone, the small steps for introduction are important. The most successful way to teach young children (who have never ridden and also need to develop balance skills) is 'walking' the bike' first, then add additional elements and skills. This brings confidence and comfort as each element adds to the overall skill.
As Martianone noted, have the pedals temporarily removed from your trike. Have the seat adjusted so that you can sit and also place your feet onto the ground. Find a smooth, flat area without major obstructions. If available, a large, empty parking lot area is perfect for these exercises.
You may need some help in getting the trike there, or find a similar spot close to you. Even a wider side walk with good turnaround spots would work - stay off active streets.
While sitting on the bike, 'walk' it for a distance. After a short distance turn the bike while walking, to walk it back to the start point. After doing that a few times, do the same exercise, but allow the bike to 'coast' a short distance, by lifting your feet as the bike glides forward. This is the perfect time to learn to use the brakes, by very gently/lightly applying brake lever pressure, as you feel the effectiveness of the braking action. Gentle and smooth, let that develop.
take a break, let the tension of learning slip away. DO it all again.
Once you've become comfortable with 'coasting' in a straight line, slowly add 'turning' while coasting, all the while using 'braking' to keep your speed comfortable and controlled.
Do that for a while...
AN IMPORTANT ELEMENT: DON"T look down at the bike. ALWAYS have your visual attention to where you are going - LOOK FORWARD. If you start looking down, STOP. Recognize that you're looking down, and bring your attention forward again!
All this can be done in multiple sessions, until you've become comfortable with each additional element.
When you feel quite comfortable with all this, go to a different spot, with a different, but similar environment, and do all of the same elements again, Coasting, braking, turning.
When this again becomes comfortable, have your pedals put back on the trike.
Go back to the 1st exercise spot - Now, instead of 'walking' the bike, pedal slowly, allow the bike to coast, applying the brakes smoothly, and work towards turining the biek while coasting and then also pedaling.
You're now riding the bike/trike. What comes next is using your skills to ride in differeing environments. Go to the 2nd practice spot and do it all again.
You will become comfortable in riding in varied environments.
IMPORTANT - Try to do this every day, weather-permitting. Frequent practice is what develops your motor-balance skills body memory. Do it as often as possible!
DO think about falling, don;t worry about what will happen.
Wear a helmet, wear gloves. If you wear pants, make sure the pants leg on the side where the chain runs, is lightly secured to your lower leg and calf. Where you bought your trike and helmet will surely have velcro straps to help lightly secure that pants leg.
It WILL all be exciting and wonderful !!! Have wonderful time learning ! Learning is always the best of times !
Ride On
Yuri