making a simple wysiwyg text box

hi im looking on how to make a wysiwyg textbox where i can have each line in the textbox wrapped with <p>

and also how would i bold everything before the ":" on each new line
kinda like tumblr.com "chat" posting box except they make it into a list, which is not what i want

Perhaps you should be more descriptive and specific about what you're looking for help with.