help internet startup

please help every time i start up my computer the sheild icon in red comes up as if i am trying to get to some web page the site is (helper security) advast says warning malicious site but after i check warning it keeps comming back. what should i do?? anyone help please i am not the best with computers

It shouldn’t be happening with any site… can you post the urls (links) that you’re not being able to access.
Is your avast updated?
Do you have any other antivirus in this computer? Had in the past?
Which firewall do you use?