Malignant tumors shows metastasis but benign tumor not. How do I know if I have a benign tumor?

Benign tumor? Although benign tumors can be observed and do not normally metastasize, the best way to confirm is to have a biopsy.
By symptoms felt. I assume that you thought that because you have symptoms of some growth somewhere...The only way one can really tell benign from malignant in a strictest sense of the word is to look at it with a microscope and have a pathologist look at it...But simply put a benign tumor is a growth with a very very slow rate of cell growth unlike malignant tumors that grow fast and spread to different places.