Once you created the supplier under People > Suppliers, you have to go in the Services tab (on the left).
There, you enter the services provided by this supplier and you click on the "Update matches" button, on the right.
You define all the matches applied by the supplier and you click on the Save button.
You then go in the job concerned to outsource it (using the "Outsourcing" tab on the left). You select the supplier in the list and, when you arrive in the outsourcing details of the job, click on Edit > Matches (or "Matches from a CAT tool analysis").
That's where you can define the matches for the job, by selecting the match category and defining the number of words (or lines or another unit) for each category.