This aspect presents a very unique challenge to the parents of an autistic child. Needless to say, it is difficult to accept the fact that your child is afflicted with autism, but of course as parents, you want to do everything you can for your child to allow them to lead as normal a life as possible. Some parents are even in denial of the fact that their child has autism, but the quicker you as parents can accept that fact, the sooner you can deal with it and get the specialized help that your autistic child needs at this point in their development.
As a parent, you may need to develop a thick skin. What this means is that some people in the general public will make rude remarks or comments about an autistic child. While most people will accept that fact and be helpful and sympathetic, you need to be emotionally prepared for the occasional thoughtless jerk who makes a rude or crude comment about your autistic child. It does you no good to get angry or embarrassed or to cause a scene, and you need to be pacified with the fact that the jerk who made the comment makes himself look incredibly stupid to others via his remark.
One of the ways to allow your autistic child to learn how to act and behave in the general public is via role playing at home. You can pretend to be at a social gathering such as a school picnic and do role-playing, which will allow your child to become comfortable with this setting gradually over a period of time. Keep your role playing sessions short at home, since the attention span of an autistic child is limited, and forcing them to continue with it after their attention is exhausted will simply put a negative spin on being in such a social situation, which is the opposite of what you are trying to achieve.
One of the traits of an autistic child is that they do not look people in the eye. It is unknown why this is the case but it is thought to perhaps be a function of the child actually realizing that they are not the same as their peers, and this aspect is a reflection of a sign of low self-esteem. While there is no way to prove that via scientific studies, that is a popular train of thought. Whatever the cause though, you may want to work with your child at home, and perhaps even with a reward system for when they are able to look you in the eyes. The model of "proper behavior warrants a reward" has been effective for many, but do not make the reward large, just something very small, like being allowed to play with their favorite toy.
It will take work, but as parents, you have the ability to help shape your child's future. Do not put the entire task on the shoulders of the school, but rather, work with your child at home to create a pleasant and loving atmosphere, and to work with your autistic child to help them function.