I am so frustrated!

Ugh! I've been trying for days now to get this bokeh thing down. I can't for the life of me figure it out though. I've looked at several tutorials on how to do it and I still can't get it it. It's really making me angry. I feel like a failure. It seems so simple yet I haven't been able to do it. Does anyone have any advive for me? Any tips?

Thank you!

P.S.
If it helps, I have a Nikon D3000.