Do you have a starting point? Do you know what side of the family it would be on, and how far back? Do you know where they may have lived? Because the only way to really prove this, is not by DNA, because DNA doesn't prove anything other than having DNA in common, and you may not have inherited the Native American ancestors' DNA that would be on the particular genes that contemporary DNA companies use to specifically check for ethnicity marker purposes, let alone for Native American DNA, and each company uses different calculators, and can provide wildly different results. The most solid way, takes just old fashioned researching your family tree, and looking at marriage records, census records, birth/death records, and then checking tribal rolls, government documents, newspapers, lineage books, etc.