1. Open iFile




2. Goto the location/Dir of the file you wanna change permission.




3. Click the little blue arrow near the file, you will see a page like this :




4. Scroll Down, The permission in this screenshot is 644 :




5. Change permisions; in this screenshot, its 775



Common permissions:

644
User: Read, Write
Group: Read
World: Read

755
User: Read, Write, Execute
Group: Read, Execute
World: Read, Execute

775
User: Read, Write, Execute
Group: Read, Write, Execute
World: Read, Execute