Information about the school system in Sachsen in different languages can be found here: https://www.schule.sachsen.de/1752.htm
The legal guardians enrol their child at the primary school responsible in the school district where the child is resident. Place and time of the school registration are announced by the cities and municipalities every year in May or the parents receive an invitation from the primary school responsible for the residential district. Registrations take place in the period from 1 August to 15 September in the year before school enrolment (https://amt24.sachsen.de/web/guest/leistung/-/sbw/Grundschule+Anmeldung-6000057-leistung-0 ).
Children with special educational needs must also be registered at the relevant primary school. If the special educational needs have been determined, the parents decide whether their child should be enrolled at the regular school or a special school (https://amt24.sachsen.de/web/guest/leistung/-/sbw/Foerderschule+Anmeldung-6000521-leistung-0).