First of all create a new layer.
Than edit->fill->new window opens->choose under contents: use "pattern". now you get all your "uploaded" pattern and can choose one of them.
If you have downloaded some new pattern and they do not appear on your assortments klick on the little arrow below, and then the small arrwow-button on the right. choose "prest manager"* and load one of your pattern-files form your directory.
after all you press done, or... if you didn't have to load a new pattern just "okay". and there it should be.

I hope thats what you were lookning for.
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