Swapping ETH to BNB

Dear Metamask,

I have now Etherium on my metamask account which i want to transfer to BNB.
I can only pay for this transaction with BNB which i don’t have yet.

Is there anything i can do to solve this?
My goal is to spend this on pancakeswap, there it’s even worse. it calculates the swap in costs in Eth, i did it a transfer that left me with 300% of needed amount and it still says unsufficient funds.

Please help me.
thanks in advance.

Kind regards, Tasso