How do I potty train my 20 months toddler? Whenever I place her on the potty, she'll start screaming and wailing & grabbing my neck tightly. :(

I didn't train my three kids ... for my thinking up to them . they are age 8,6 n 5 ... my girl age 8 stop diaper at 4 even bed time by herself but my two son still wearing diaper to sleep ... I dun find it a must to train them .... they will know when they are ready no point forcing them .... I just wan them to happy