It is considered courteous to post a reply if you have been able to resolve your problem, or received an answer to your question. If you were given multiple suggestions/solutions, it is also helpful if you would list the solution that worked for you.
Once you have posted those details, when still looking at your thread, near the top of your thread you'll see Thread Tools. Click the down arrow to expand the drop down menu, at the bottom of it you'll see Mark this thread as solved. Click on it to mark your thread as solved.
If later you find that the problem has returned, and you had previously marked your thread as solved, follow the steps above. Instead 'Mark this thread as solved' you will see that in this case Mark this thread as unsolved is listed.