JS: CryptoNightMiner-A TRI

Hello, could I get help please? I really don't know what to do.
It says threat secured we've safely aborted connection on because it was infected with JS:CryptoNightMiner-A [TRI]. I close the window but it appears again and again.

 

Hello Autumn,

We would like to more information regarding this.
Provide the screenshot of AVG threat detection window to assist further.
Click on "see details" on threat detection window and provide its entire screenshot.
You can post the screenshot here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions.