I need help creating a Student Information Database for a medium size school

Hello everybody!

I am very new to base and databases in general. Yet I am trying to build a relatively simple database for a school. The school has around 2500 students and is working at the moment with excel sheets to manage the student data and their grades. I feel like I know what I want to have but I severely lack the knowledge to make it happen and thus struggle at the simplest things.

For example: in MS Access I was able to use a form to have a drop down selection while having the option to add a new value which was then stored as a new line in the corresponding table. I tried this here with the combobox (and the listbox) but if I understand it correctly the newly entered value is only stored in the memory and not in the table.
Another very simple thing is that I wanted to normalize my table so I made a separate table for Nationality etc. which works fine but in the Students table I only manage to see the ID instead of the name.

I would appreciate if somebody could take the time to look at my work so far and help me make it better. I am very grateful for any input, help, recommendations, sources or anything else that comes to mind.
I will gladly provide more information about what and why I did what I did so far.

They only want a way to look up a student and seeing all their information in one place: Personal Data, Payment Information and Grades. Ill attach a file that shows how they store the data so far.

My prototype so far:
Test-2.odb (26.6 KB)

Forms:
FormStudentData: Is the first form I made which almost works. I feel like if I could replace the foreign keys of the columns Nationality, From Highschool and Skill / Major with the actual name it would almost be usable.

Student Data: Is where I am currently trying to show the data in a more presentable form. Very experimental and not working as intended. Specially the combobox is broken since it always returns the entry to 0 and I dont know why.

School data:
Information for Data base.xlsx (24.7 KB)

Thank you!

Some background information about me:
I am a swiss librarian with minimal training in SQL and databases volunteering at the Bright Hope Institute in Cambodia. They have no funds and dont own MS Office. Thats one reason why LibreOffice Base was recommended to me. I would love to set them up with not just a working database but a decent database but for that I need some help. I know that these questions are probably very basic for some of you and that I could find the solutions myself somewhere out there but I only have three weeks and they would like me to not only make it work but show them how they can do it themselves in future. Thats why I feel like I need to accelerate the process by asking for help. Thanks in advance!

Thanks
Adrian

First, just a little tip:
Do not use identical field identifiers for “ID” in different tables.
Example, you use:
TblStudents → StudentID
TblGrades → StudentID
distinguish, e.g.:
TblStudents → SStudentID
TblGrades → GStudentID


English documentation

Right, good tip. Thanks I will correct that!