For clustering, you need to have multiple sequences from different species. Find the same gene you have in different species.Try running clustalw/x

If you have no experience I would recommend using previous work (which I always prefer, even if I have experience with something). The UCSC genome browser would be a great place to find what you need. Start by locating your sequence (either by looking up the region or finding it using BLAT) and then make sure that the conservation track under the Comparative Genomics section if in full mode, in the browser you would be able to find similar sequences under the "multiz alignment of 100 vertebrates" track, click on it to get more information.