I am not sure about your site, it's seems very fishy for me. no details found, and looks very unprofessional.

and "Our company will cover all the transfer fee." make me suspicious...

The site is clearly not legit, they claim to be covering all fees only to have a few people to try them out. The site is also designed without any efforts and will likely charge back once you send them your coins 

Your site says "SellBitcoin.us (SellBitcoin.us Ltd.) is a company made by Mike Maples,Jr." along with a picture. You mean Mike Maples as in @m2jr, right?
I really doubt a site so unprofessional and without SSL was created by him. Please post a link to your site from the account @m2jr. Until you do that your site must be considered a scam.

Even if the site were legit, you need to gain some trust first. Nobody will/should send first to a new site, there's no guarantee they will receive anything in return. Always use escrow.