The Plie is a very basic exercise and is the first you would learn in a traditional studio. The kitchen is a great place to start practicing this move; using the hard floor as your "ballet floor," face either a table or a counter and hold the edge of the surface gently as you stand with your heels together and turn your toes out as far as you can. The goal is to turn your toes away from each other, as if to form a straight line. Because ballet is about precision, form, and lines, it is essential to perform this and all moves with perfectly straight posture.
Simply build on what you learned above by getting your body into a plie, and then rising to the balls of your feet. This exercise targets and strengthens the legs, ankles and feet. The use of a surface to hold onto---even if only slightly---is recommended to help maintain posture and balance.
To create a Battlement Tendu, stand as if in a Plie and slide one of your feet in font of and parallel to the other foot, so that your feet are touching heel to toe (this is called fifth position). Next, stabilize your weight on one foot and slide the other in front of your body as far as you can, then directly out to the side, and finally behind your body before returning it to fifth position. Don't forget to repeat this move on the opposite side and to keep your toes pointed at all times. This exercise warms the dancer and will improve turnout of the hips.
A basic Rond de Jambe is a build on the Battlement Tendu. Position yourself as if doing a Battlement Tendu, and using one foot to stabilize on, circle your other perfectly pointed foot slowly from the front of your body to the side of your body and follow through with the circle with your pointed toe gently skimming the floor until finally, without lifting your toes from the floor, finishing the exercise again in the Battlement Tendu position. This exercise primarily focuses on the turnout of your hips. Make sure to repeat it on the other side.