Expose your puppy to different surfaces. One of the first behaviors we teach our pups is "Box" or "Table". This behavior transfers to the agility pause table. Lure pup up on a low pause table, treat them on the table. You can call the pause table anything you want. (If I was starting over I would name the pause table "Box" instead of "Table" for my dogs because on the agility course there is the potential to have too many "T" words, i.e. tunnel, tire, table, and teeter. The problem is I am also a creature of habit, and under pressure revert back to my default words, "table" would be one of them.)
Teach your pup to "Box", meaning to get up on a variety of obstacles. In our training field we use "Box" for upside down kennel tops, the bottom of barrels turned upside down, bird crates, and more. Be creative with your pup, get them to get up on all kinds of surfaces, exposing them to different shapes, sizes, and textures. Once your pup is comfortable getting up on a "Box", then you can begin to ask them to sit on the box also.
You can also begin to use Buja boards for motion training. Buja boards are generally made from plywood, 36" x 36" with a painted surface or covered surface. On the underside, there is a 2x4 box where a partially deflated ball is placed. This enables the Buja board to rock gently. At first you can reward your pup for getting one paw on the board, then reward for two feet and eventually all four. Depending on your pups temperament will determine how fast they get comfortable on the Buja Board.
Perch training can also be started with young pups. The Perch is generally a 1'x1' wood surface that is raised by 2"x4"'s underneath. So the Perch is about four inches in height. The Perch helps teach pups rearend awareness. Again, you can reward your pup for getting one front paw on the perch and then the other. Perch training is mostly used with just the front paws on the Perch.
These are just a few behaviors you can teach your young pup. Exposure to a variety of surfaces and heights will help your pup build confidence in his future agility training.