visual studios c++ help

hello i have a question that i hope someone can figure out. i am having a problem building my code (or any code) so i can execute it. i have downloaded many tutorials and tried building them and i get the same error many times

LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/Lesson34.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

that is the error i get. when i compile it i hey 0 errors 0 warnings but when i try building it never works. if someone knows some settings i am supposed to change or something i didn’t do please let me know.
all the code i have tried works fine on my friends computer, and i have uninstalled and reinstalled visual studios but still get the same thing…thank you in advance