Need Help TP strategi coding

hello all....
I need help coding for my strategi TP coding.

The strategi :

buy = 1 in market price 1000
TP = 20
If market price up to 1020 , the EA not colose posisition.
If market price up to 1021 or high and then go down to 1020 or more , the EA must close position on 1020.

I need EA closer like that with extern TP = ...

any body can help me pls..... maybe this strategi can help another user....

Thank's

use trailingstop...