The markbook is capable of storing weighted grades and setting the weights on a per-class basis, be sure to enable the weighting options in School Admin > Markbook Settings. Teachers can then setup their markbook as needed and enter marks.
If you don’t plan to use the Markbook and the teachers already have the marks calculated, you could setup criteria in Reporting Cycles for them to enter the marks directly into the Reports module.
The Reports module is flexible and powerful, but since nearly every school in existence seems to design and generate their report cards differently than other schools, it can take some customization work to setup the reports as you need. My recommendation would be to start by checking out the docs and the Reports module first to familiarize yourself with how everything here works, and then see what might need custom template assets for your school.