EDIT : found the solution
var htmlImage = token_form.addField({
id: 'custpage_htmlfield',
type: ui.FieldType.INLINEHTML,
label: 'HTML Image'
});
htmlImage.defaultValue = "custom text";
In Suitelet ,Any idea how to add text to describe a field like "Enter the full name : " , i could not find a field type for this , if i give TEXT as field type , it is giving me a input text box rather than a normal text .
var field = form.addField({
id : 'custpage_textfield',
type : serverWidget.FieldType.TEXT,
label : 'Text'
});