Avast Error: System is Not Protected

I am running my computer with various issues and as I searched for a no-cost program application that can help me utilize and fix those issues, I installed Avast Free Antivirus.
When installed successfully, an error “Unsecured. Your System is not protected. Please use the Fix Now button start protecting your system. Urgent: Avast Service stopped. The Avast Antivirus program has been stopped or is in an inconsistent state.
Please re-start the program to resume protecting your system.” appeared on it. Why is it that I am still unsecured when I have already downloaded Avast properly?
Please help.

