I guess it's because I haven't put enough but someone can explain what I have to do here ?
If you are not in hurry, just wait. There is no need to waste more money on transaction fee.
If you are in hurry, right click on your transaction and select "Increase fee". Currently, you need to pay around 15 sat/vbyte if you want your transaction to be confirmed in the next block. (A new lock is mined every 10 minutes on average.)
Note that the fee rate required for a fast confirmation depends on network state and changes over time.