in visual studio i cannot use the functions of get and set whilst coding in c#

Im currently trying to create a class in App_Code and create to a private parameter a get and set function. no matter what i tried doing to fix the issue i cannot make the get and set function to work. i have tried to repair my visual studio installation and uninstall and install it twice now. i added and removed all workloads that i can download in an attempt to fix the issue to no avail. i have everything that is related to coding on c# in visual studio yet i cannot write the basic lines of get value and set value.