var color = myDocument.colors.add();
color.properties = { model : ColorModel.PROCESS, space : ColorSpace.RGB, colorValue :[0,0,0]}
var paraStyle = app.activeDocument.paragraphStyles.add();
paraStyle.fillColor = color;
paraStyle.fontSize = 32;
paras = myFrame.paragraphs;
for (i =0 ; i< paras.length, i++){
paras[i].appliedParagraphStyle = paraStyle;
}
Just in case you what to do what to apply style to a range of para(character style)
var charStyle = myDocument.characterStyles.add();
charStyle.fillColor = color;
paras[i].characters.itemByRange(0, 10).appliedCharacterStyle = charStyle;
For further details of the available properties refer: http://jongware.mit.edu/idcs6js/pc_ParagraphStyle.html