make functions dependant on one another

Im using jquery and am trying to make some function to fire after each other. DOes the following seems right. I'm pretty much calling a function in a function.

  $j = jQuery.noConflict();
            var obj;
            var items = new Array();


            $j(document).ready(function() {
                                
                function setTopicsSpans() {               
                    // do stuff
                    //.....
                }
                
                function ajaxGetTopicRatings() {
                    var request = $j.ajax({
                        url: "json.php",
                        type: "GET",
                        data: {"items": items},
                        cache: true,
                        contentType: 'application/json; charset=utf-8',
                    });                    
                    request.done(function(data) {
                        //console.log(data);
                        obj = jQuery.parseJSON(data);
                        setTopicsSpans();
                    });
                    //......
                }
                function setTopicsArray() {
                    $j('[data-tid]').each(function() {
                        items.push(this.getAttribute('data-tid'));
                    });
                    ajaxGetTopicRatings();
                }
                
                setTopicsArray();
                
            });

Now I read a bit about callback functions. but when I put in put in for example "setTopicsSpans" in function ajaxGetTopicRatings(setTopicSpans) I get an an error that the function: "setTopicsSpans" doesnt exist. Anyone have an idea how to do this?