Many people have asked about how to do this, so here's the solution:
1. Choose Catalog and Then Categories:
2. Go as far to the right of the item you are looking to move and find this:
3. Next, choose which arrow you are looking as a move up or down
3a. Double Up Arrows up moves that item to the very top
3b. Single Up Arrow moves the item up just one space
3c. Single Down arrow moves the item down one
3d. Double Arrow down moves the item all the way to the bottom
Once you've moved that item to where you want it, Save and Exit and that will now have moved the item to where you want it to be in your catalog. You can repeat this for any item or category for all of your items.