After finish scanning with free version of the Clamwin, I can only "save the report" or "exit", what do I need to do to have Clamwin fix the virus?

You can configure ClamWin's infected files option in the General Preferences to Report Only, Quarantine, or Remove. The default is Report Only, and you should usually leave it at that to prevent losing access to your Windows operating system if there is a false positive detection of one of the important Windows files.

You can verify detections by uploading a copy of the file to Jotti or VirusTotal where they will scan the file with multiple antivirus programs, including Clam AV (the engine for ClamWin). If several other AVs also see an infection, it is probably a real infection and not a false positive. Jotti is at https://virusscan.jotti.org/en on the web. VirusTotal is at https://www.virustotal.com/ on the web. I like to see at least 5 AVs besides Clam AV confirm an infection.

If the infection is real, you can then set ClamWin's infected files option to Quarantine or Remove and rescan the file or directory concerned. Be sure to change the option back to Report Only afterwards.

If the infection is false, report/upload it to Clam AV starting at https://www.clamav.net/lang/en/sendvirus/ on the web. Clam will correct the false positive within a day or so.

Version 0.96 of ClamWin (in beta testing now) will protect against false positives of important Microsoft files, so you can set to Quarantine/Remove without any problems, but you will still need to upload false positives to Calm Av for correcting.

Regards,