We as cryptocoin enthusiasts are bound not only to earn cryptocoins but we also sell them for whatever reason we like. We sell our coins generally to convert them soon for fiat or cash so that we can use them for our own purposes and sometimes we sell them just to trade the resulting coin back to create more earnings.
This is just how we sell and I sell my coins at Bittrex in one sweep and you can follow based on the screenshots that I have made. Once you see the pictures, you can now do your own selling positions so that your coins could sell in its entirety rather than in portions.

Here you just input how many coins that you wanted to sell.
Then you click "Limit" and then choose "Conditional"

After that, choose "Less than or Equal to"

Then input in both fields in how much price you wanted to sell your coins.
You will see the total in BTC how much you will get when the sell order gets executed

Finally you will have to confirm your order.
You can read the condition of your trade there.

Photo credits: Bittrex.com