From nothing to the storefront in four steps.
Reaching Mars takes four steps.
Download Tor Browser only from the official Tor Project site, verify the signature on the first install, and set the security level to Safest. A normal browser cannot open an onion address. Mars works fine at Safest.
Copy an address from the verified list, never type a fifty-six character string by hand. Open it, and cross-check the address the page header prints against your bar before your password. The header print is Mars's way of showing you the address it believes it is serving.
Mars Market