You can get the computer name from within the application. Declare the Win32 API modul on Declare -> Local External Functions

Function boolean GetComputerNameA (ref string lpBuffer, ref ulong nSize) Library "kernel32.dll"

Now write this code:
string ls_temp
ulong lul_value
boolean lb_rc

lul_value = 255
ls_temp = space(255)
lb_rc = GetComputerNameA (ls_temp, lul_value)
messageBox ('Computer Name', ls_temp, information!)