How to change your comment box..
If you want more of a decorated comment box, then click 'edit profile' scroll down to 'text input background image' and paste the direct link of your image in. Your comment box will then have that design inside it. You can use any image you want really, so just find an image then get the direct link of it and you can use that (if you don't know the direct link upload it to tinypic/photobucket) Here are some images you can use..
Ice creams
http://i302.photobucket.com/albums/nn106/oceanavenuex33/Comment%20Boxes/cbx15.jpg
Love hearts
http://i180.photobucket.com/albums/x204/FreakProduction/Comment%20Boxes/3f2f7611.gif
One direction
http://i797.photobucket.com/albums/yy252/Thalita028/One%20Direction%20S2/q25.jpg
Stripes
http://i1167.photobucket.com/albums/q634/Halzrawr/Backgrounds/612682osgi4uu2w9.gif
Flowers
http://i715.photobucket.com/albums/ww155/heidemarie2009/imagesCAUDTJSZ.jpg
Summer Beach
http://i793.photobucket.com/albums/yy214/jairo_aze101/summer-wallpaper-1280x800-0911070.jpg
Love hearts
http://i557.photobucket.com/albums/ss11/Empathy_Love/Love/love-wallpaper22.jpg
Colour splash
http://gi0006.photobucket.com/groups/0006/G5PAK3TBQS/rainbowpuddle2.jpg
Hollister model body!
http://i896.photobucket.com/albums/ac166/maackk/I-homeHeroCenter.jpg
Sponge bob
http://i160.photobucket.com/albums/t168/cnava03/sponge_bob.jpg