Read and follow the instructions here carefully.
http://community.48months.ie/t5/The-Knowledgebase/My-Internet-is-not-working/ta-p/45928If it still doesn't work then you're doing something wrong so double check the steps.
Those instructions are guaranteed to configure things correctly if followed precisely.
If you still can't get it working then post your settings here for review.
Screenshots are the best if possible.
Hope this helps.