Style attributes in JS

Now I need to assign a value to this tag, whose content is:
1. The text to be displayed is "hello world ";
2. span's background-color: red, and also: border: 1px solid #333333; cursor: hand;

I need to assign values to them in <script> </script>. How can I write them? Do you want:
Document. getElementById ("a"). style. background = "red"; to write one item?
Can I write the style all at once? How can I write it?
Solution:
1. Define a CSS rule first, and then this. className =''
2. document. getElementById ("a" ).style.css Text = "border-collapse: collapse; border-spacing: 1; border: 1 solid #0B2565; background-color: white; color: black ;"