try and download the "blink" sketch, it will load for 5 seconds then say "Serial port "Com1" not found"
The 5 seconds is the IDE compiling the sketch and then trying to load. It doesn't take more than 1 second for the Uno to get updated with the Blink sketch.
i look through files and found out my arduino is on Com4.
What files did you look at? The only place you can determine what com port the Uno gets assigned is in the Device Manager. Verify that when you plug in the Uno it shows up on the Com Port devices (in Device Manager.)