when I start Arduino UNO connected with my laptop, then I followed instruction choice the Board type on Arduino IDE and the instruction said choose the port, but port is unclickable. can someone help me?
You first need to read the posts at the top of the forum to add any additional information you can.
No ports in the IDE can often be a clone board that requires additional drivers.
Other common mistakes are USB cord broken or not fully inserted.
If its a clone with micro USB then the cord should be DATA and POWER as some are power only.
Reading a few posts in the forum is suggested as this comes up quite often and the fix is usually quite easy.