I want to hear that all goes well.
Bring you horse in from the fields. Give him a wash and a good groom. Trim his hairs. Make him look pretty.
Clean his tack and wash your own riding gear.
Then prepare him. Lunge him first in a training arena - use a pessoa and a bridle with a soft bit - if you know how. But check his fitness.
Check his feet, his breathing, his back and his mouth.
Also check that his tack fits.
Choose from your riding friends a good rider, who owns a well schooled horse and ask him/her to ride with you. Explain it is your first for a little while - if they don't already know.
Pick your route. Plan the ride with your friend. Feel confident and safe.
Choose a nice day for your outing.
When you are ready - go and enjoy your ride. Not too many canters, mind for even random ice is slippery.
And tell us all about it.