You can find the Forsaken Cave North West West of Windhelm and South South West of Winterhold:
There are no major puzzles in this cave. The main problem that you will be faced with is killing a strong draugr just before you get to the wall with the word of power. In that room you will find around 6 or 7 enemies that will attack you at once. They also use a shout that disarms you which actually caused me to have to replay the whole dungeon because I had lost my good sword. Be sure to save frequently save during the fight to avoid having to redo a a large part of the dungeon.
In terms of killing the group of enemies, I always go for the weaker targets first and make sure I avoid the stronger opponents by moving around a lot whilst slaughtering the normal and restless draugr. To avoid getting hit I usually strafe in and out of the range of my enemy so that there is only a small window in which they can hit me. Whenever I am within range I will swing my sword. Be sure to keep an eye on your health and use health potions as needed. I often get surprised by low health when I am facing lots of enemies because I am not aware of the people behind me hitting me. I usually like to retreat and heal with magic because it is free and levels up restoration instead of using health potions which can be sparse. You can see this tactic played out in the video below, it is at around the 8 minutes and 25 seconds mark in the video.
Full Walk Through YouTube Video: