error code 10 when trying to upload arduino program to computer.

When i was uploading my arduino uno program into computer. After it finished it sayed it couldnt download all the way. And then said error cod 10. Its now under ports. In device manager. and has a little ! and says Arduino UNO (Com4) I just mainly need help with the uplaoding and all. If someone could explain it out to me. That would be great becuase ive read directions from The arduino website and it is not working. Im on step 4. on the arduino website. Using arduino uno, So if eny one could help me out that would be great.