Update page 'Costs'

Costs.md

@@ -0,0 +1,33 @@
+![Costs Help Image](https://raw.githubusercontent.com/CS-4820-Library-Project/Libly/master/images/CostsHelp.png)
+
+The costs page allows for cost data to be added to or removed from the database. 
+
+## Adding cost data to or removing cost data from the database
+
+Select a report type.
+
+Select a vendor.
+
+Select a year.
+
+Select a name (for DR, database; for IR, item; for PR, platform; for TR, title). Names that already have costs data for the selected year appear in bold.
+
+* Enter the cost in the original currency (capped at 999999999.99).
+
+* Select or enter the original currency.
+
+* Enter the cost in the local currency (capped at 999999999.99).
+
+* Enter the cost in the local currency with tax (capped at 999999999.99).
+
+All these fields must be filled to add data to the database. The criteria for filled are that the costs are greater than zero and there is an original currency entered. To remove data from the database, all costs must be set to 0 and the original currency field must be empty. You can easily clear all the fields using the **Clear** button.
+
+If you want to go back to the costs in the database after making a change and before saving, you can click the **Refresh Costs** button.
+
+To send your addition/removal request to the database, click the **Save Costs** button.
+
+## To add a list of costs to the database
+
+You can import a list of costs from a TSV or CSV file into the database by using the **Import Costs File** button. The file must contain all the fields appropriate to costs for that report type: vendor, year, name (database/item/platform/title, depending on the report type), cost_in_original_currency, original_currency, cost_in_local_currency, and cost_in_local_currency_with_tax. The fields must be named exactly in the first row of the file. Each cost must be valid to be added to the database.
+
+A good way to use this is to send someone else your costs data from the files in your "./all_data/costs/" directory, where "." is the directory the program is installed in. These contain all the costs data in your database.