Use a tool like apk-signer from the Google Play Store.
Download the main "UCCW - Ultimate custom widget" app from the Google Play Store. Download uccw495 sign apk
Long-press on your home screen, select Widgets, and choose a UCCW widget size. Select the imported skin from the list. Signing an APK Use a tool like apk-signer from the Google Play Store
Download the specific skin file (often a .uzip file) you wish to use. go to Settings > Backup/Restore
Use apksigner from the Android SDK build-tools to sign and zipalign the file.
Open the UCCW app, go to Settings > Backup/Restore, and select the downloaded skin file to import it.