A lot of agility is essentially nothing more than a 4-foot target behavior. Getting on a table, going into a tunnel or through a hoop, getting on a contact obstacle. Think of this behavior as a whole-body target and train it just like a nose-touch where your criteria is that your dog gets on (or in) a specific target area.
Be sure you have worked your crate training skills first as this will enable you to use your puppies willingness to offer to go somewhere as a foundation for sending them to new places.
Start with sending to something that has very definite boundaries - such as a crate or table, where the criteria can be very clear (you are either in -or on - or not).
Even in the early stages, you might consider what body language works well for directing them or at least what will be consistent with your cues in agility. Here are some specific body language cues to be aware of:
-stepping with the leg closest to the dog and using the arm nearest to them to send them.
-facing and moving into the dog’s path tends to push them away from you, curling your shoulders, turning away from the path, leaning away or moving away - tend to pull your dog into you.
-crossing behind the dog, tends to turn their head to see where you went and changes their path accordingly (try it when they are ahead of you on leash)
An important piece of this learning is sending the dog - without you going with them to that place.
Start with very short sends (a foot or two) and work up to more distance and more directional control (ie: send them out around a tree on the way to their place)