Do not treat filters as "magic buttons." The manual explains the math behind Gaussian Blur, Unsharp Mask, and Whirl & Pinch. Understanding the parameters lets you control results rather than guessing.
Detailed instructions on layer masks, alpha channels, and script-fu. gimp user manual download
There are three primary ways to access the manual: , Offline (HTML) , and PDF . Here is the correct method for each. Do not treat filters as "magic buttons
Install the file. GIMP will automatically detect the local files the next time you launch the program. Key Sections to Study First gimp user manual download