On your Indexes Tab, you can add or delete Indexes for your Table. 
MySQL does not allow changing/modifying of existing indexes. So all functionality you have on this tab is to add or drop indexes. In the Name column you can specify an Index name. In the Column column, you can pick your table columns on which you wish the index to be formed. And in the type column you can specify your index type, ex. primary key, normal, unique etc More informational type columns for indexes are available, but hidden, you can unhide them using the Customize option.