Use a program like 7-Zip (free) or WinRAR .
Ensure you have part1 through the final part in the same folder. TWMK22WEB72.part2.rar
Right-click the .part1.rar file and select "Extract Here" (or similar). The program will automatically combine the parts and extract the content. Use a program like 7-Zip (free) or WinRAR