Help Please :) Restricting Add Link to Admin only

Hi there, I wondered if any of you would be able to help me please.

I have recently installed and am trying to customize a matrix theme gallery.

http://www.craftystash.com/gallery2

I have added the link items plugin to it, but would like to restrict the access for this just to admin if possible.

My gallery is not active as yet from my site as I wanted to be able to fine tune it before it is available.

I hope I have given you enough information to be able to help me, if you do need anything else though, please just let me know - but I must warn you, I'm not very clued up on a lot of the technical speak.

Thank you so much, I really appreciate you taking the time to help me with this.