Plz anybody give me a easy tips for potty traning?

I have a 4 years daughter......so many way i tried to give her potty traning but i failed.....her problam is she sit on the potty.....but she hold her pee and poe.......last 2 days i froced her to use potty.....and nighttime she had a high fever...my dr told me she hold her pee thats why she had a fever.....Dr told me if she dont use to potty so dont forse her......when she will ready she do it herself......she still use diaper......plz give me any advice....