Update through_purchase_department.md

through_purchase_department.md

@@ -5,4 +5,20 @@ If you can't purchase for your own account, because you need to go through a ded
 In means, there will be:
 
 * a "billing contact" (in general, the purchaser email). This account will have access to invoices. And this is the account which make the purchase.
-* a "technical contact", the email of the system administrator using the solution and making support requests.
+* a "technical contact", the email of the system administrator using the solution and making support requests.
+
+
+## As "billing contact"
+
+When you created an account as a purchaser (eg: "purchase.dept@example.com"), you need to go inside the member zone:
+
+![](member_purchase.png)
+
+Now, **click on the Purchaser tab**:
+
+![](purchaser_button.png)
+
+Your request will be sent to us, and we'll unlock you the purchaser feature.
+
+As soon it's unlocked (you will be notified), return to the "Purchaser" tab, you should see a different interface:
+