Make a new document and make sure the extension is .html. Next type this in:

<html>
<head>
<title> Your Title Here </title>
</head>
<applet code="yourgame/YourGame.class" archive="yourgame.jar" width=410 height=465></applet>
</html>

All that's left to do is you need to change yourgame to the name of your project (changing uppercase letters to lowercase), YourGame to the name of the java file, and yourgame.jar to whatever you called your jar file.
For example, if you called your project Pong and your java file was Pong.java and you called tha jar pong.jar it'd look like this:

<applet code="pong/Pong.class" archive="pong.jar" width=410 height=465></applet>