Q: Virus on MacBook

Please provide more detail of why you think yo have a virus or Trojans.

Do you have an anti-virus app installed?

Run this and post the results here so we know more about your configuration.

http://etrecheck.com/

EtreCheck

https://discussions.apple.com/docs/DOC-6172

Keep your Mac OS up-to-date with OS X and securities patches to protect against Mac specific threats

Installing a 3rd party anti-virus has in most documented cases on these forms shown to cause far more problems and false reports than any security benefits they purport to fix.

You may also try Malwarebytes for mac to remove malware and adware that the software can identify. This software does not protect you against these types of programs, but it will not interfere with the normal operations of OS X like Anti-Virus program tend to do on mac.

malwarebytes.com

As suggested above you may include an etrecheck report for further analysis and practice safe browsing habits. If you are lured to sites or ads that offer free prizes, free software, free files, free downloads they commonly like to bundle adware, junk ware and malware with these offerings.

To add to the suggestions, "Lots of messages" sounds like you're getting browser pop-ups claiming that your computer is infected. Usually, with some toll free number they insist you call NOW, NOW, NOW!!! to fix the problem.

If this is the case, it's a scam that has no purpose other than the fleece you out of as much money as possible to "fix" something that doesn't exist.

There is no software in the world that can tell what is on a remote computer through a web browser. Any pop-up or web page making such claims is a lie. Period. These types of scams also try to lock your computer to that page by making it impossible to dismiss the pop-up, or navigate away from the page. This is not an infection of any kind. It's just a JavaScript trick to keep you in a loop.

Force Quit Safari. Hold the Shift key down and relaunch it. Holding the key tells Safari not to load any previous pages.

Please read Phony "tech support" / "ransomware" popups and web pages.

If that describes what you're experiencing, it's a scam.