I am wanting to go to de'arnise hold to help Nalia on her quest but I can't get out of the city. I talked to her already and told her we would meet her there. I went on other quests, and now I am ready to help her but can't leave the city. I have already traveled to the city gates as someone advised me earlier but this did not open up de' Arnise Hold. What do I need to do to travel there?

Are you sure that when you travelled to the City Gates you clicked on the wheel icon at the edge of the screen, and then moved your mouse to the right to see the D'Arnise Hold, Trademeet, Windspear etc. on the map?

Is the hold on your map? If it is, and doesn't turn blue when your mouse is over it, you need to go to the city gates AGAIN and leave from there. Once in the keep area you need to meet Nalia south of the keep in a small wooden fort, rather than attempting to go in via the raised drawbridge.

Hope this helps