Adding a new package for WPDM - Premium Package is as same as adding a new package for Download Manager Pro plugin, excepts you have to specify settings related to Premium Package. For adding a new package for Download Manager Pro you can refer to this post Add New Package. Below is the detailed description for how to add/edit a package for Premium Package plugins. For rest of the options/settings you can follow the instruction here: Add New Package

1. Step 1 : Goto Admin Menu Downloads Add New to add a new Download Manager package or Downloads All Packages then click on package title you want to edit to edit any package.
2. Step 2 : Goto Package Settings section/metabox. You can notice a new tab named Pricing & Discount here.Please check Pricing & Discounts Docs for more details
3. Step 3 : Finally click Publish or Update button to save/update package.