You can activate items by clicking the ab up the top called 'Shop'.
Then on the left will be a list of links. Click the one called 'Deactivated' under the heading 'Inventory'. Then you should be able to see the items that you have bought. Now simply clikc activate on the items and they should move to your active inventory.
If you can't follow what I just said then you can google 'activate items toribash' or anything along those lines to get answers. 99% of the time here the question you have in mind has already been asked so it always pays to search for your question first.
Activate them by going to "Deactivated" In the inventory in the shop tab. Click activate and you should see them. If you still can't see them ingame, do /dl (Usernamehere) Without the parenthesis.