Advice for booking experiences

Hello redditors,
I am visiting Peru in a month and since we didnt book via travel agency I am having trouble understanding how to book in advance some of the experiences we want to have.
How do you guys booked them via whatsapp? We have booked MP and the rails
Also we have a spare day at lima and are thinking of daytriping to Huacachina.
I got a bit overwhelmed with so much info and I would love to get maximum enjoyment since we are Europeans and probably wont visit Peru (if we dont fall in love with it) for many years if at all