Merging, or importing, registry files (REG files) into the existing system registry on your computer allows you to quickly add any number of additional entries to the registry without the hassle of having to perform the additions manually.
Click the "Start" menu.
Type "regedit" in the "Search" box and press "Enter." Select "Regedit" from the list to open the program.
Click "File" on the menu bar and select "Import" from the drop-down menu.
Select the registry file you wish to merge with the existing registry and click "Open."
Registry files may also be merged with the system registry by double-clicking the REG file.