You want to buy steem with your savings so you can convert it to your currency?
Go to your savings and click the little arrow to the right of the amount. Click market. On the left hand side you will see Buy Steem.
With your savings you should be able to buy 80 steem at the rate now. You will need your key to finalize the transfer. The 80 steem will be added to the steem you already have.
Good luck and let me know how you make out.
Maybe someone else can explain this better.