Major problem

i am creating a mysql chat script and i have got all the mysql functions under control. i have the script that will chack if another user has posted (by checking the database) then refreshing if it has, but i find this doesnt work to well and so i want to just update the text field on the form, not the whole page. has any one got any ideas i thought of using a goto statement that goes back to a certain part of the page but i cant find any goto info anywhere.