Welcome to the forum! There are a lot of great people here willing to lend a hand anytime. Often using the search box (in the toolbar at the top right-hand side of every page) will lead you to the answers you're looking for. If not, feel free to post a question in the appropriate area.
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Regarding your question, not sure who your cellular provider is, but did you buy/add/setup a "hotspot" account? Carriers charge for tethering. You probably have, but just checking. Can you use other broadband apps on your iPad? When you say "use the link", do you mean tapping on the iPad's Safari icon or do you mean you're trying to use a link from somewhere else, such as inside an email? Post a few more details and I'm sure you'll get some responses and get it sorted out.
Welcome again and enjoy!