I have tried withdrawal of various coins and it keeps asking me for an address so i insert my wallet address to receive the coin but keeps saying cancelled. Admin says i'm using the wrong address. Please can someone advise what address thay are referring to?
It's the destination address, which is, the address where you want your coin to be transferred to. I would strongly suggest you to copy and paste it and not typing them one by one as it's very case sensitive and typing will make your coins went to someone else's wallet. And, O believe you know about this already, you can only send to and from the same coin. Which means, don't send your doge to lite, or your dash to btc address.
If i try withdraw a coin it says withdrawal amount and then states receive the same coin after the fees? Why would i want the same coin if i am withdrawing it?
Do you mean the column below the word "obtain" ? It simply states the final amount you'll obtain on the destination address, which will not be equal of the amount you send because they will deduct it with transaction fee. Hence, they help informing you the exact amount you will receive using that column
So if i use lets say my coin base BTC receive key for BTC it will work?
Understand now. So dash i can only send to a wallet that accepts dash as a coin and that has a dash wallet?
How do i trade a coin lets say dash for doge or eth. This site only allows BTC to eth?
. . . . . . . . . so... Your problem was, in fact, as simple as trying to send your btc to a doge address (or something in that line) ? Well, it's ok, people learn from mistakes. Sorry, didn't try to be rude, I just find it hilarious.
Seriously now, yes, you can ONLY send btc to a btc address and dash to dash address. Other than that, you'll be in trouble. Which also answered your second question: NO, you should only send to DASH WALLET. So, although the exchange has dash on their list, you can't just simply send your btc to your dash address on that exchange and wished that you will be credited with dash. You still have to send your btc to the btc address and dash to dash address, no matter what. If you have btc and want to "convert" them to dash, then you have to invest on btc first, and exchange your btc to dash after your account got credited.
About your third qestion, I haven't trade on yobit for quite some time, so I don't know how they work right now, but I think you can get other pairs (a btc-to-dash or doge-to-eth are what we call as pairs) without having yo convert them to btc first. They have those "tabs" on the top list of their market price, the one with "RUR" "BTC" "ETH" "USD" WAVES", click the one you desired (let's say "eth") and you'll see what eth pairs are available (means, eth-to-other-coins). I don't see a dash pairs, though, so maybe you have to exchange your dash to btc and then exchange your btc to doge.
A little suggestion, though, move to a better exchange like bittrex or kraken. Their interface might be slightly more intimidating than yobit, but they are saver. If you read few pages behind, you'll see that yobit is having some issue with withdrawal and stuck transaction, although some people also claimed they were improving.
yobit is safe 
