You'll need to open your Coinbase account, go to the option to deposit bitcoin, and copy the address which they provide you with. Go to the send tab in Electrum as described above and paste in the address you copied from Coinbase. Manually check the entire address to make sure it is exactly the same as the one being shown to you by Coinbase. Then hit "Max" to send all your funds, then hit "Pay" to select an appropriate fee and finalize the transaction.

If you are not in a desperate rush, then given the mempool is frequently emptying out at the moment, choose the minimum fee of 1 sat/vbyte to save as much money as possible.

Also, reconsider your decision to store all your coins on Coinbase, since by storing all your coins on a custodial exchange you don't really own your coins, but all you really own is an IOU from Coinbase.