Your post is unclear.
What exactly do you mean by "add credit to my credit roaming"?
That doesn't really make any obvious sense.
What exactly do you mean by "credit" here?
Cash credit?
Membership plan?
Data or call minutes add-on?
You can see how to add all of these here:
Membership plans include some amount of roaming data.
If you use up that roaming data then you can buy a data add-on to continue using data while roaming.
I don't know if that addresses your query but if not then please clarify your query further and explain exactly what you're trying to do and what problem you are facing.
