Health insurance is cover by my parents how do i show that they have insurance on me

If your parents have a regular policy (not Obamacare or a marketplace policy) and you are under 26 and can be carried on their policy, then your parents should have received a 1095-B or 1095-C showing that you were covered. 

The IRS does not require you, in this case, to supply proof of coverage. If they ever ask, get a copy of the 1095-B or 1095-C and send it to them.

In your case, all you should need to do is to say that you had Health Insurance coverage all year, in the Health Insurance interview (at the top line near Wages & Income and Deductions & Credits). 

If, on the other hand, your parents' policy was from the marketplace (Obamacare), then they should have received a 1095-A with your name on it. In this case, the IRS will expect form 8962 from you to justify whatever premium tax credit that you received (which was probably none). If your parents asked a tax professional with help on their return, you might ask that same tax professional how you fill out the 1095-A entry section such that none of the PTC is allocated to you.