How kan a download the schets from a programmed uno
You can't download the sketch from the Uno because the Uno doesn't contain the sketch. What the Uno does contain is the binary that the compiler generated from your sketch. However, that binary will not in any way resemble your sketch. Practically, the only use for the downloaded binary file is to program other Unos with the exact program that's on the Uno you have.
If you want instructions for downloading the binary from the Uno, I can provide them on request.