If you're using the text editor, there should be options similar to the ones in this text box that will allow you to use bold and italics. If not, you'll need to use HTML codes to do it. For example:
< b>bold</ b>
< i>italics</ i>
(Without the spaces in the brackets)
To add a banner, you'll have to upload the banner to your own photo host like Photobucket then link back to it in your summary using HTML. Be sure to read the banner rules so your banner is the correct dimensions before you link it, or it'll be removed.
To link an image in your summary use this code:
< img src="
http://www.thelinktoyourbanner.com">
(Again, without the space next to the bracket)
