Here i have given the the example of start notepad.exe
System.Diagnostics.Process p = new System.Diagnostics.Process();
p.StartInfo.FileName = "notepad.exe";
p.StartInfo.Arguments = @"C:\Users\XYZ\Desktop\hi.txt";
p.Start();
p.Close();
here, you can define fullpath of exe in Filename Propery of StartInfo.
if an Exe application is taking any command line argument then you can also give Arguments.
here i have given the filename. so notepad is opened with that file.