[UMG] how call function of bp widget from level blueprint?

I made a widget blueprint and function in it (that function create widget and show it to user). In level blueprint from “event begin play” i try call that function, but function don’t have execution pin, here’s a screenshot for example Oops!

To be more clear - i try this guide with making list of buttons from array A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums , but want call list creation right after begin play tp check how things look.