Modify my exsisting EA for MT4

I have an EA currently working well. However, I would like a couple of additional features added.

My EA currently does this.

Opens a trade, based on MACD

Sets a TP and SL, accourding to my settings

Will NOT open a 2nd trade, on the same currency pair, if one is still running.

This is what I would like to add......

When the trade goes a certain amount of pips, in my favour, I want it to

adjust the SL, to break even, or to the amount of pips, I've specified in the settings

So for example, as default, i've set my SL at 500 pips

when the trade is 500 pips in my favour,(or whatever i've set it to in the inputs tab)

I want the SL to automatically move, to

+100 pips, (or whatever i've set it to in the inputs tab)  ensuring that i make a small profit. or break even.

this will be set by the user, in the inputs tab.