Select this button, then choose the pic you want to attach. (Pics should not be too large because they will just get scaled down anyway. I think mine are 600 pixels wide max).
Btw, this is the button that disappeared awhile for me. I think it was some programming anomaly by chess.com but now it's all OK.
I don't see it either. This is what is on my screen https://ibb.co/TP6zZ21
The image is under the blue letters "imgbb". Also the link buttons are also missing, but links automatically work after you add a space after the address.
It's possible those aren't available to new accounts to limit some spam and potential abuse.
I don't see it either. This is what is on my screen https://ibb.co/TP6zZ21
...
Yes, that's exactly what I saw when I was having the problem. I never changed anything from my side (no new PC, no new browser) so I think it's related to chess.com. But I'm surprised it works for me now, but not for you. 
I don't see it either. This is what is on my screen https://ibb.co/TP6zZ21
...
Yes, that's exactly what I saw when I was having the problem. I never changed anything from my side (no new PC, no new browser) so I think it's related to chess.com. But I'm surprised it works for me now, but not for you.
The quoted member's account was just two days old. That is the likely cause for the options being gone in that case.
I cant send links or anything and I'm on school computer
It's possible your school is blocking things
Found out it's a new safety feature. You'll need to play some more games and make more regular posts to get the option.
Great news vickalan!