You can add and delete individual terms and adjust weights within weight sets that you create.
To add a term to your weight set:
On the Search Workbench tab, select Term Weights from the Show menu.
In the Term Weights, go to Term Weights > Your Weight Set.
Enter a term. When you begin typing the term, a new line appears below it, on which you can enter more terms.
Assign the weight. The range is 0 to 100, with 100 having the highest weight or influence in the search. The colored icon and Weighting Effect column changes to reflect the effect of the assigned weight.
Click Save.